
Class 
Book 



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; 




RICHARD ANTHONY PROCTOR 



Science •, Front is — Vol. 14 



OTHER WO R LD S 
THAN OURS 



BY 



RICHARD A 



, PROCTOR, 



B.A., F.R.A.S. 




NEW YORK 
P. F. COLLIER & SON 

M C M I I 

14 






By Transfer 
Maritime Comttl, 

SEP 3 1940 



r 



5 




"Lo, these are parte of His ways: but bow 
beard of Him? the thunder of His power who can 

=— Job xxvi. 14. 



portion is 
V 9 



J 



CONTENTS 



Introduction 17 

I. What the Earth Teaches us 23 

II. What we Learn prom the Sun ........ 86 

HI. The Inferior Planets < ... 73 

IV. Mars, the Miniature op our Earth < 100 

V. Jupiter, the Giant of the Solar System .... 138 

VI. Saturn, the Ringed World 165 

VII. Uranus and Neptune, the Arctic Planets .... 183 

VEIL The Moon and other Satellites 193 

IX. Meteors and Comets; their Office in the Solar 

System 309 

X. Other Suns than ours 338 

XL Of Minor Stars, and of the Distribution of Stars 

in Space 366 

XII. The Nebula: are they External Galaxies? ... 390 
XIII, Supervision and Control 313 



ILLUSTRATIONS 



Chart of Mars, on the Stereographic Projection . . 109 

The Planet Jupiter (Browning) 152 

The Galactic Cloven Flat Ring {plan) 270 

The Galactic Cloven Flat Ring (section) 270 

The Galactic Flat Ring, Modified in Accordance with 

the Observed Peculiarities of the Miley Way . . 272 

The Milky Way Regarded as a Spiral 276 

Drift of the Stars in the Constellations Cancer and 

Gemini 286 

Observed Proper Motions of Stars in Ursa Major and 

Neighborhood 287 

Observed Proper Motions of Stars in Head of Aries . 288 



PREFACE 



The general purpose I have had in view in writ- 
ing the present treatise will be gathered from the in- 
troductory pages; but I wish to offer here a few 
remarks on certain points of detail. 

It will be seen that, on many of the subjects 
dealt with in this work, I have propounded views 
which differ from those usually accepted. I have not 
done this from any love of novelty, nor from any 
desire to attract attention by bizarre or fanciful the- 
ories. Each of the new views here presented has 
been the result of a careful study of the subject dealt 
with, and I have searched as anxiously for considera- 
tions opposed to any novel theory as for arguments 
in its favor. If others should be more successful 
than I have been in finding reasons for rejecting any 
of my views, I shall be ready to abandon them with- 
out regret. I trust I am free from that weakness 
which forces a man to regard every theory he has 

(5) 



6 PREFACE 

once advocated as a matter to be defended at all 
hazards. No weakness more mischievously affects the 
work of the student of science. As Faraday said, 
"Truth should be the primary object of the philos- 
opher' ' ; and this can never be the case if, where he 
imagines he holds a theory, the theory has in truth 
possession of him. 

Some among my readers will recognize, in the 
views here presented, the growth of ideas which I 
have dealt with consecutively, with more or less 
fulness, in the pages of several quarterly, monthly, 
and weekly serials, and in one of our leading daily 
newspapers. I refer to this, because it has happened 
to me several times lately to be accused of plagiarism, 
when I have had occasion, in developing fresh ideas 
on a subject, to repeat statements which (unknown 
of course to my accusers) had proceeded from my 
own pen. It is not often one is accused of steal- 
ing one's own ideas, but that is a pleasure I have 
more than once been enabled to enjoy of late, 
and I here present my compliments to those who 
(anonymously or otherwise) have afforded me that 
luxury. 

Wherever it has been in accordance with the 
custom of any journal, however, I have always writ- 
ten under my own name. 

Since the manuscript of this work was placed in 



PREFACE 1 

the printers' hands, I have obtained fresh evidence 
on some of the theories dealt with in the following 
pages. 

One of the most surprising phenomena ever wit- 
nessed by the telescopist — a phenomenon I had read 
of long since, but had not thought of in connection 
with my subject — seems to me to afford stronger evi- 
dence than any adduced in the text, in favor of my 
theory that the major planets are subsidiary suns 
supplying heat (if not a minute proportion of light 
even) to their satellites. I refer to the observation 
made by Admiral Smyth, that on one occasion the 
second satellite of Jupiter, twelve minutes after en- 
tering on the disk of the planet, was seen outside the 
limb, u where it remained four minutes, and then sud- 
denly vanished." Two other equally competent ob- 
servers, Maclear and Pearson, witnessed the same 
phenomenon. "Here," says Webb, " explanation is 
set at defiance." But it is precisely where explana- 
tion seems set at defiance that the true student of 
Nature is most hopeful of gaining instruction. The 
observation is very startling, it is true; and the 
explanation may be expected to be also surprising. 
But I think it is not far to seek. The satellite cannot 
have retraced its course; Jupiter cannot have shifted 
his place; our atmosphere cannot be in question: 
surely, when all these explanations are eliminated, 



8 PREFACE 

our task is rendered easier instead of more difficult. 
A change of shape in Jupiter, corresponding to that 
which I have endeavored to exhibit as explaining 
Saturn's occasional assumption of the square-shoul- 
dered aspect, would obviously account for the phe- 
nomenon. We know that Schroter suspected an 
apparent flattening of portions of Jupiter's outline. 
Here we have an effective confirmation of that long- 
doubted observation. If we consider the matter 
rightly, the observation made simultaneously by 
Smyth, Maclear, and Pearson, makes that view all 
but certain which in the text I have presented only 
as a highly-probable hypothesis. 

In preparing the Maps for my new Atlas (now 
nearly ready), I have detected signs of systematic 
aggregation among stars visible to the naked eye, 
which seem to me to place beyond all question the 
fact that Sir William Herschel adopted an erroneous 
hypothesis as the basis of his system of star-gauging. 
The fact that about one-third of the lucid stars are 
collected in a region having the greater Magellanic 
Cloud nearly in its centre, and covering less than 
one -sixth of the heavens, has never yet, so far as I 
am aware, been noticed. Supplemented by other 
facts, detected during the work of transferring the 
stars of the British Association Catalogue to my 
j, the existence of this rich region around the 



PREFACE 9 

Nubeculse disposes at once of the hypothesis of a 
generally uniform distribution within the sidereal 
system. I shall be enabled, by Mr. Brothers 's kind- 
ness, to illustrate my Lecture on the Stars at the 
Koyal Institution on May 6th by means of photo- 
graphs of the Maps which thus conclusively (at least 
in my opinion) establish the theory that there exist 
special and discernible laws of aggregation among the 
lucid stars. 

I may add in this place that it is not the case, as 
has been recently asserted, that my theories respect- 
ing the sidereal system have been founded on the 
discovery that certain nebula3 are gaseous. That 
discovery, so far from being opposed to the theories 
of Sir William Herschel, afforded most striking evi- 
dence of his wonderful reasoning powers, since he 
had been led to express his firm conviction that 
many nebulaa are gaseous, had confidently asserted 
that the Orion nebula is so, and had even antici- 
pated the discovery of the variability of the ir- 
regular nebulae, recently effected by Le Sueur of 
Melbourne. 

My theory respecting the sidereal system has been 
based on the signs of systematic aggregation among 
the lucid stars, and of a more intimate association of 
those stars with the Milky Way than could be ex- 
pected were Sir William Herschel's fundamental the- 



10 PREFACE 

ory correct. My first paper on the subject, in the 
Intellectual Observer for August, 1867, was entitled 
"Notes on Star-Streams"; and it was only while 
inquiring into the nature of stellar aggregation that 
I was led to notice the laws of nebular distri- 
bution, and so to inquire into the relations between 
stars and nebulae. I take this opportunity of 
thanking my kind friend, the editor of the In- 
tellectual Observer and Student, for the exceptional 
liberality with which he has found a place for 
views professedly opposed to generally • received 
opinions. 

The theory brought forward in the chapter on 
Meteors and Comets is not altogether new. The 
general idea on which it is grounded has been dealt 
with by Mayer and Thompson, while the relation 
between the motions of discrete bodies and the for- 
mation of systems of orbs has been dealt with by Sir 
John Herschel, in considering his father's hypotheses 
respecting the nebulae. That idea, however, pre- 
sented itself independently to my mind when I was 
writing my treatise on Saturn (at which time my ac- 
quaintance with scientific literature was very limited 
indeed), and is definitely stated in Note B of the 
Appendix to that work. The line of reasoning is 
wholly new, I believe, by which I have endeavored 
to show that those peculiarities of the solar system 



PREFACE 11 

which have hitherto been regarded as affording the 
strongest objection to the hypothesis of development 
may be regarded as in reality the direct result of the 
processes by which the solar system has reached its 
present condition. In the preface to my treatise on 
Saturn I touched on the possibility that some such 
explanation of those peculiarities might be found, 
remarking that in the rings of Saturn astronomers 
may one day recognize the action of the processes 
by which the solar system has attained its present 
state. 

In the chapter on the Sun I have entered at some 
length into the subject of the solar corona, partly 
because that subject is full of interest in view of the 
approaching total solar eclipse visible in the south of 
Europe, and partly because I have seen with regret 
that an erroneous theory of the corona has been 
recently promulgated, which seems likely at the 
present conjuncture to affect mischievously the prog- 
ress of research into this interesting question of solar 
physics. 

I have heard with much pleasure that the As- 
tronomer Eoyal, at the last meeting of the Astro- 
nomical Society, altogether repudiated any share in 
starting this theory. Although I had seen his name 
associated with it, I had always thought it incredi- 
ble that a mathematician so skilful and clear-sighted 



12 PREFACE 

should have advanced or adopted so ill-considered 
a hypothesis. 

I here tender my best thanks to Mr. Brothers, 
F.E.A.S., for his careful revision of the proof-sheets, 
and the detection of more than one error which had 
escaped my scrutiny. 

Richard A. Proctor. 

London, April 12, 1870. 



THE PLURALITY OF WORLDS 



OTHER WORLDS THAN OURS 



INTRODUCTION 

ASTKONOMY and Geology owe much of their 
charm to the fact that they suggest thoughts 
of other forms of life than those with which 
we are familiar. Geology teaches us of days when 
this earth was peopled with strange creatures such as 
now are not found upon its surface. We turn our 
thoughts to the epochs when those monsters throve 
and multiplied, and picture to ourselves the appear- 
ance which our earth then presented. Strange forms 
of vegetation clothe the scene which the mind's eye 
dwells upon. The air is heavily laden with moisture 
to nourish the abundant flora; hideous reptiles crawl 
over their slimy domain, battling with each other or 
with the denizens of the forest; huge batlike creat- 
ures sweep through the dusky twilight which con- 
stituted the primeval day; weird monsters pursue 
their prey amid the ocean depths: and we forget, as 
we dwell upon the strange forms which existed in 
those long past ages, that the scene now presented 
by the earth is no less wonderful, and that the 

(17) 



18 OTHER WORLDS THAN OURS 

records of our time may perhaps seem one day as 
perplexing as we now find those of the geological 
eras. 

Astronomy has a kindred charm. We cannot in- 
deed examine the actual substance of living creatures 
existing upon other celestial bodies; we cannot even 
picture to ourselves their appearance or qualities; 
and only in a few instances can we even form any 
conception of the conditions under which they live. 
But we see proofs on all sides that, besides the 
world on which we live, other worlds exist as well 
cared for and as nobly planned. Nay, we see globes 
by the side of which our earth would seem but as a 
tiny speck; we trace these globes as they sweep with 
stately motion on their appointed courses; we watch 
the return of day on the broad expanse of their sur- 
face; and we see systems of satellites which are sus- 
pended as lights for their nocturnal skies. We 
further find that our sun is matched by a thou- 
sand thousand suns amid the immeasurable depths 
of space ; and the mind's eye pictures other 
worlds like those which course around the sun, 
travelling in stately orbits around his fellow-lumi- 
naries. 

Long, however, before the wonders of modern 
astronomy had been revealed to us, men of inquir- 
ing minds seem to have been led, as by an irresist- 
ible instinct, to examine into the resemblance which 
may exist between our world and other worlds sur- 
rounding it on every hand. It has not been the 
mere fanciful theorizer who has discussed such 



INTRODUCTION 



19 



questions, but men 
science. In long 
Pythagoras studied 



of the highest eminence in 
past ages Anaximander and 
the subject of other worlds 



Huyghens, Galileo, 
the same interest- 
day, Whewell and 
scientific and dia- 
theories upon the 



than ours; later, such men as 
and Newton have dwelt upon 
ing theme; while, in our own 
Brewster have employed their 
lectic skill in defending rival 
subject. 

Undoubtedly a large share of the interest with 
which the question of other worlds than ours has 
been regarded, is due to the fact that, as the science 
of astronomy has progressed, the subject has con- 
tinually presented itself under new aspects. The 
question, in fact, is one of those which are ever new 
and ever old. It has all the charm belonging to sub- 
jects which men in all ages have delighted to discuss, 
while it is associated in the most intimate manner 
with the progress of modern science. With what a 
charm of novelty, for instance, the discussion between 
Whewell and Brewster invested the subject! No 
doubt a large portion of that charm was due to the 
personal qualities of the two disputants. Yet, despite 
the skill with which each of them presented the ar- 
guments belonging to his own side of the contro- 
versy, few could have read with any interest a 
discussion on a subject so well worn, had it not 
been that the arguments were drawn from the dis- 
coveries which had recently been made by astron- 
omers. Nor was it uninteresting to notice how these 
discoveries at once seemed to acquire a new interest 



20 OTHER WORLDS THAN OURS 

when they were associated with the subject of life in 
other worlds. Facts which had attracted little notice 
at the time of their discovery at once assumed im- 
portance, when it was seen how they bore on the 
rival views which Whewell and Brewster were en- 
forcing. The interest with which the public regard 
many of these discoveries may, indeed, be said to 
date from the controversy between those eminent 
men. 

No very long interval, if we count by years, has 
elapsed since the " Plurality of Worlds" and "More 
Worlds than One" were written. Yet so rapidly has 
science progressed, that already the subject of life in 
other worlds has assumed a new aspect. Arguments 
which were hypothetical thirty years ago have either 
become certainties or been disproved. Doubtful points 
have been cleared up; a new meaning has been found 
even in those facts which were well known to both 
the disputants; and lastly, a new mode of research 
has been devised, which has not only revealed a 
number of surprising facts, but promises to work 
yet greater marvels in the years which are to 
come. 

One is thus invited to discuss anew a subject 
which but a few years since seemed thoroughly sifted 
by the inquiries of the two eminent philosophers I 
have named. We stand in a position much more 
favorable for the formation of just views than that 
from which Whewell and Brewster surveyed the plan- 
etary and stellar systems. Never, since men first ex- 
plored the celestial depths, has a series of more 



INTRODUCTION 21 

startling discoveries rewarded the labors of astron- 
omers and physicists than during the past few years. 
Unhoped-for revelations have been made on every 
side. Analogies the most interesting have brought 
the distant orbs of heaven into close relationship with 
our own earth, or with the central luminary of the 
planetary scheme. And a lesson has been taught us 
which bears even more significantly on our views 
respecting the existence of other worlds: we have 
learned to recognize within the solar system, and 
within the wondrous galaxy of which our sun is a 
constituent orb, a variety of structure and a com- 
plexity of detail, of which but a few years ago 
astronomers had formed but the most inadequate 
conceptions. 

My object, then, in the pages which follow, is 
not solely to establish the thesis that there are other 
worlds than ours, but to present, in a new and I 
hope interesting light, the marvellous discoveries 
which have rewarded recent scientific researches. 
Judged merely according to their direct significance, 
these discoveries are well calculated to excite our 
admiration for the wonderful works of God in His 
universe, and for the far-reaching scope of the mental 
powers which He has given to His creature Man. 
But it is when we consider recent discoveries in 
their relation to the existence of other worlds, 
when we attempt to form a conception of the 
immense varieties of the forms of life corre- 
sponding to the innumerable varieties of cos- 
mical structure disclosed by modern researches, 



r 



22 OTHER WORLDS THAN OURS 

that we recognize the full significance of those 
discoveries. Although the growth of our knowledge 
is ever accompanied by a proportional growth of 
our estimate of the unknown, we seem already 
entitled to say that we have 

Come on that which is, and caught 
The deep pulsations of the world, 
jEonian music, measuring out 
The steps of time. 



CHAPTEE I 



WHAT OUR EARTH TEACHES US 



BEFOKE proceeding to consider the various cir- 
cumstances under which the worlds or systems 
which surround us appear to subsist, it may 
be well to inquire how far we have reason to con- 
clude, from the consideration of our own earth and 
its inhabitants, that the Creator has designed the 
orbs which exist throughout space for the support of 
living creatures. 

It would not be just to argue directly from the 
fact that the earth is inhabited to the conclusion that 
the other planets are inhabited also, nor thence to 
the conclusion that other stars have, like our sun, 
their attendant worlds, peopled with various forms of 
life. An analogy founded on a single instance has 
no logical force. And it is doubtful whether we 
have not, in the moon, an instance which would as 
effectually serve to support a directly opposite con- 
clusion. It seems all but certain, as we shall pres- 
ently have occasion to show, that no part of the 
moon's globe is inhabited by living creatures. Cer- 
tainly she is inhabited by none which bear the least 

(23) 



24 OTHER WORLDS THAN OURS 

resemblance to those existing on our earth. Thus it 
might fairly be urged that, since one of the two orbs 
respecting which we know most appears to be unin- 
habited, there remains no probable argument in favor 
of the view that other orbs besides our earth are the 
abode of living creatures. 

Yet the earth in reality supplies an argument of 
great force, when we consider the evidence she pre- 
sents in another light. The mere fact that this world 
is inhabited is, as we have seen, little; but we shall 
find that the way in which life is distributed over the 
earth's surface is full of significance. 

If we range over the earth, from the arctic regions 
to the torrid zone, we find that none of the peculiari- 
ties which mark the several regions of our globe suf- 
fice to banish life from its surface. In the bitter 
cold within the arctic circles, with their strange alter- 
nations of long summer days and long winter nights, 
their frozen seas, perennial ice, and scanty vegeta- 
tion, life flourishes in a hundred various forms. On 
the other hand, the torrid zone, with its blazing heat, 
its long -continued droughts, its strange absence of 
true seasonal changes, and its trying alternations 
of oppressive calms and fiercely-raging hurricanes, 
nourishes even more numerous and more various 
forms of life than either of the great temperate zones. 
Around mountain summits as in the depths of the 
most secluded valleys, in mid-ocean as in the arid 
desert, in the air as beneath the surface of the earth, 
we find myriad forms of life. 

But this is far from being all. Various as are the 



^ 



WHAT OUR EARTH TEACHES US 



25 



physical habitudes which we encounter as we travel 
over the surface of our globe, we are able to trace 
the existence of other varieties even more remark- 
able. The geologist has been able to turn back a 
few leaves of the earths past history, and, though 
the pages have been defaced and mutilated by Time's 
unsparing hand, he is yet able to read in them of 
many strange vicissitudes to which the continents 
and oceans of our globe have been exposed. But, 
far back as he can trace the earth's history, and al- 
ready he counts her age by millions of years, 1 he 
finds no evidence of an epoch when life was absent 
from her surface. Nay, if he reads aright the mys- 
terious lesson which the blurred letters teach him, 
he is led to believe that, at the most distant epoch 
to which his researches have extended, there was the 
same wonderful variety in the forms of life as at the 
present day. He can, indeed, find the scattered re- 
mains of only a few of those old-world creatures; 
but he recognizes, in those which have been pre- 
served, the clearest evidence that thousands of others 



1 The results of the recent deep-sea dredging expeditions, though 
they have an obvious bearing on the question of the relative ages of 
the various strata of our earth, do not appreciably affect our estimate 
of the range of time during which this world has been the abode of 
living creatures. We can no longer assume that adjacent rocks which 
differ in character are necessarily different in age: but we have enough 
evidence, from superimposed strata, to prove the enormous antiquity 
of the earlier formations. The researches of Dr. Carpenter and his 
fellow-workers have a most important bearing, however, on the subject 
of the present chapter, and supply a more forceful analogy, perhaps, 
than any dwelt on in the text, in favor of the view that, under the 
widest varieties of condition, Nature may be most prodigal of life. 

Science — 1 — 2 



26 OTHER WORLDS THAN OURS 

must have existed around them. He knows that, of 
a million creatures now existing, scarcely one will 
leave to future ages any record of its existence; he 
sees whole races vanishing from the earth, leaving no 
trace behind them; and he is thus able to form an 
estimate of the enormous extent by which the creat- 
ures and races of which he can learn nothing must 
have outnumbered those whose scattered remains 
attest their former existence upon the earth. 

Here, then, we have analogies which there is no 
mistaking. We see that not only is Nature careful 
to fill all available space with living forms, but that 
no time over which our researches extend has found 
her less prodigal of life. We see that, within very 
wide limits, she has a singular power of adapting liv- 
ing creatures to the circumstances which surround 
them. Nor is this lesson affected — like the general 
lesson drawn from the mere fact of the earth's being 
inhabited— by anything we can learn from the aspect 
of our satellite. For the arguments against the pres- 
ence of living creatures on the moon are founded on 
the evidence we have that the physical habitudes of 
that orb are outside the limits — wide as they seem 
to be — within which Nature can effect the adaptation 
we have spoken of. 

In fact, if we consider rightly, the argument which 
has been drawn from the moon's presumed unfitness 
to be the abode of living creatures is so founded on 
terrestrial analogies as to leave the contrary argument 
unaffected. We have to assume that the argument 
drawn from the analogy of the earth is forceful be- 



WHAT OUR EARTH TEACHES US 27 

fore we can form any opinion at all respecting the 
moon's habitability. And, in any case, no argument 
can be drawn from the moon's unfitness for the sup- 
port of life, against the view that, where orbs fit for 
the support of life exist, there Nature has provided 
such classes of living creatures as are adapted to the 
special habitudes of those orbs. 

The moon teaches us, however, that the Creator 
has not intended all the celestial bodies to be at all 
times habitable. The sun also teaches the same les- 
son. And it is necessary that we should consider 
how far the evidence presented by our own earth 
may serve to elucidate this teaching. We shall see, 
as we proceed, that terrestrial analogies afford a very 
sure guide in the midst of many perplexities which 
the study of the worlds around us presents to our 
contemplation. 

Let us trace out the various degrees of fitness or 
unfitness for the support of particular forms of life, 
which we recognize in various regions of our earth. 

Often, where there exists so slight a difference 
between two regions of the earth that, to ordinary 
observation, it would appear that the forms of life ex- 
isting in one should be well adapted to the other also, 
we yet find that this is not the case. Some minute 
peculiarity of soil, or climate, or vegetation, will 
render one region absolutely uninhabitable by a race 
which lives and thrives in the other. Darwin men- 
tions several instances in which an apparently insig- 
nificant change in the circumstances under which a 
particular race has thriven, and sometimes a change 



28 OTHER WORLDS THAN OURS 

which does not, at first sight, appear to be in the 
least connected with the well-being of the race, has 
led to its gradual disappearance. And it seems de- 
monstrated that even the slow processes of change 
to which every part of the earth is subjected would 
suffice to destroy a number of the races now subsist- 
ing on its surface, were the characteristics of those 
races unalterable. But, as the physical habitudes of 
their abode slowly change, the various races of living 
creatures slowly change also, so as to adapt them- 
selves continually to the varying circumstances under 
which they live. 

The lesson taught us by this peculiarity is very 
obvious. On the one hand, we see that it would be 
by no means sufficient to indicate a general resem- 
blance between the physical habitudes of our earth 
and those of some far-distant planet, in order to 
prove that that planet is the abode of living creatures 
resembling those on our own earth. But, on the 
other hand, we are taught that the existence of dif- 
ferences sufficient to render a distant planet an un- 
suitable abode for such creatures as we are familiar 
with cannot force upon us the conclusion that the 
planet is uninhabited. On the contrary, the circum- 
stance we have been considering teaches us that such 
differences as would suffice to banish life of certain 
kinds are insufficient to banish life of all kinds, or 
even to render less abundant the forms of life which 
exist under those changed conditions. 

And now we may proceed a step further. On our 
earth we find differences of climate and of physical 



WHAT OUR EARTH TEACHES US 2B 

habitudes generally, which are much more important 
than those hitherto dealt with. We see that not only 
would certain races perish in the long run, if re- 
moved from their own abode to other parts of the 
earth, but that, in some instances, the process of de- 
struction would be very rapid indeed. If we were 
to remove the polar bears from their arctic fast- 
nesses to tropical, or even to the warmer parts of 
temperate regions, a very few years would see the 
end of the whole race. The races inhabiting steppes 
and prairies would quickly perish, if removed to 
mountain regions. Those accustomed to a moisture 
laden air and abundant vegetation would not survive 
long if removed to the desert. 

In some races, indeed, we find a power of endur- 
ing such changes which very far exceeds that pos- 
sessed by other races. Those creatures, for example, 
which man has domesticated seem capable of endur- 
ing a variety of climate or of circumstances, which 
would destroy the seemingly more vigorous races 
which have not been subdued to the yoke of man.* 

Even man himself, however, though he possesses 
in an unrivalled degree the power of enduring in 
safety the most complete change of climate, scene, 
and circumstances, is yet limited, in a certain sense, 

1 Humboldt tells us that "the pliability of the organization of those 
animals which man has subjected to his sway enables horses, cows, 
and other species of European origin to lead for a time an amphibious 
life, surrounded by crocodiles, water-serpents, and manatees. When 
the rivers return again to their beds, the horses roam in the savanna, 
which is then spread over with a fine odoriferous grass; and enjoy, 
as in their native climate, the renewed vegetation of spring." 



30 OTHER WORLDS THAN OURS 

in his power of migration. The Englishman, for 
example, can endure the fiercest heat of the tropics 
or the bitterest cold of arctic and antarctic regions. 
But he cannot safely attempt to found true colonies 
in every part of the earth's surface. Our country- 
men in India must send their children to be reared 
in England, if they wish them to grow up strong and 
vigorous. There can be little doubt that if a thou- 
sand men and women from this country were, to 
settle in certain parts of India (not at any time inter- 
marrying with the natives), the colony would have 
disappeared within a couple of centuries. 

Here we have a second degree of unfitness, ac- 
cording to which certain countries would quickly 
become depopulated, if supplied with inhabitants 
from certain other countries. We are taught the 
same lesson as before, but in a more striking man 
ner. We see that differences exist within the con 
fines of our own earth which render particular coun 
tries absolutely uninhabitable by particular races 
insomuch that, though the individual might survive 
the race itself would quickly perish. And we see 
on the other hand, that these countries are not unin 
habited, or even less fully peopled with living creat 
ures than seemingly more fortunate abodes. 

Now, if some impassable barrier prevented the in- 
habitants of one country from visiting others, while 
yet it was possible to learn something of the condi- 
tions prevailing in other regions, how readily the 
conclusion might be reached, that some at least of 
those inaccessible regions must be wholly uninhab- 



WHAT OUR EARTH TEACHES US 31 

ited, simply because their physical habitudes ap- 
peared unsuited to the wants of the only creatures 
with which the observer was familiar. Who would 
believe, for example, that men can live, and not 
only live but thrive and multiply, in the frost-bound 
regions within the Arctic Circle, if travellers had not 
visited the Esquimau races and witnessed the con- 
ditions under which they subsist? Again, if we 
knew nothing of India, and some one pictured to us 
the intense heat of the Indian sun, the strange alter- 
nations of weather which replace to the Indian the 
seasonal changes we are familiar with, and all the 
other circumstances which render tropical regions so 
different from our English home, who could believe 
that, amid those seemingly unendurable vicissitudes, 
there are races of men that thrive and multiply, even 
as our people in their temperate zone? ' 

Therefore, in examining the circumstances of 
other worlds than ours, it will not be sufficient to 
prove that certain orbs would obviously not be habi- 
table by the races subsisting on the earth, in order to 
enforce the conclusion that no living creatures subsist 
at all upon their surface. 

Yet another step further, however. There are re- 



1 Perhaps the most striking instance of man's power of living under 
circumstances seemingly the most unfavorable is to be found in the 
fact that, though the strongest traveller is affected seriously by the 
rarity of the air at great elevations, yet races of men live and thrive 
in Potosi, Bogota, and Quito, and — to use the words of a modern writer 
— that bull-fights should be possible at an elevation at which Saussure 
hardly had energy to consult his instruments, and where even his 
guides fainted as they tried to dig a small hole in the snow. 



32 OTHER WORLDS THAN OURS 

gions of the earth where the individuals of races 
belonging to other regions quickly perish. The air 
of our own England is death to many creatures. 
And, indeed, there is not a spot in the whole world 
which would not be fatal in a brief space to many 
animals and plants belonging to other regions. Yet 
each spot, though thus fatal to certain races, is in- 
habited by numbers of others, which live and thrive 
upon its surface. 

Here, then, is our third lesson. We are taught, 
by the analogy of our earth, that it is not even 
sufficient to show that a planet would be an abode 
quickly fatal to all the living creatures subsisting 
on our globe, to prove that it is therefore unin- 
habited. 

But we have yet a stronger argument to touch 
on. There are regions of our earth to which creat- 
ures from other regions cannot be removed without 
being immediately killed. The warm-blooded animal 
perishes if placed for a brief space under water. 
The fish perishes if placed for a brief space on the 
earth. 1 What could be more wonderful to us, were 
we not familiar with the fact, than that there are 
living creatures within the depths of that ocean, 
beneath whose surface we ourselves, and the f land 
creatures we are familiar with, cannot remain alive 
many minutes? If fishes could reason, how could 



1 Perhaps the fact that there are certain kinds of fish which 
cannot only live out of water, but can travel across the dry land, or 
climb trees, affords an even more striking instance of Nature's power 
of adapting creatures to the circumstances which surround them. 



WHAT OUR EARTH TEACHES US 



33 



they believe that creatures can live in comfort in 
that element which is death to them? Yet land and 
river and sea are alike peopled with living creatines, 
each race as well adapted as its fellows to the cir- 
cumstances in which it is placed. 

We are taught, then, yet another lesson. "We see 
that, even though we could prove that every living 
creature on this earth would at once perish if re- 
moved to another orb, yet we cannot thence conclude 
that that orb is uninhabited. On the contrary, the 
lesson conveyed by our earth's analogy leads to the 
conclusion that many worlds may exist, abundantly 
supplied with living creatures of many different 
species, where yet every form of life upon our earth 
— bird, beast, or fish, reptile, insect, or animalcule — 
would perish in a few moments. 1 

There remains yet a last lesson to be drawn from 
terrestrial analogies. On the earth there are regions 
where no form of life exists or can exist. Within 



1 I might add, to the instances here cited, many others which seem 
even more striking. I have already referred to Dr. Carpenter's dis- 
covery, that in the depths of the Atlantic, where the pressure of the 
sea is so enormous that no ordinary instruments can resist its effects, 
where it had even been thought that no light can penetrate, there are 
myriads of living creatures having even organs of vision. We know, 
too, that in strong acids which would instantly kill bird, beast, fish, 
or insect placed within them, there exist and thrive minute creatures 
adapted by Nature to the strange conditions in which they are placed. 
Even in the bowels of the earth, and in the very neighborhood of 
active volcanoes, we find the volcano-fish existing in such countless 
thousands, that, when they are from time to time vomited forth by the 
erupting mountain, their bodies are strewn over enormous regions, and, 
as they putrefy beneath the sun's rays, spread pestilence and disease 
among the inhabitants of the neighboring districts. 



84 OTHER WORLDS THAN OURS 

the flaming crater of the volcano, or in the frozen 
heart of the iceberg, no living creature has its being. 
Yet even here Nature proves to us that the great end 
and aim of all her working is to afford scope and 
room for new forms of life, or to supply the wants 
of those which already exist The volcano will die 
out, and the scene of its activity will one day be- 
come the abode of myriads of living creatures who 
would have perished in a moment in its consuming 
fires. The iceberg will melt, and its substance will 
once again be peopled with busy life. But this is 
little. It is the work of which volcano and iceberg 
are the signs Which most significantly teaches us 
what is Nature's real aim. The volcano is the index 
of those busy subterranean forc33 which arc remod- 
elling the earth's frame, slowly changing the level 
of the land, making continents of oceans and oceans 
of continents, preserving and vivifying all things, 
while all things seem to suffer a gradual destruction. 
The iceberg, too, has its work in remodelling and 
fashioning the surface of new continents. But it 
exhibits also the action of Nature for the present 
benefit of the creatures which exist upon the earth. 
It acts an important part in the formation and main- 
tenance of the system of oceanic circulation on which 
the welfare of land creatures and water creatures so 
largely depends. And so of a multitude of other 
phenomena, which appear at first sight significant 
rather of the destructive than of the life-preserving 
character of Nature. The tornado and the thunder- 
storm, the earthquake and the volcano— nay, even 



WHAT OUR EARTH TEACHES US 



35 



the dreaded returns of plague and pestilence, have 
each a more powerful influence by far toward the 
preservation than they have toward the destruction 
of life. 

We see, then, that even when we can prove that 
an orb in space is so circumstanced that no life 
could by any possibility exist upon its surface; if 
it were the scene of a fierce and destructive turmoil, 
one moment of which would suffice to destroy every 
living creature now existing upon the earth; if its 
whole mass were heated to a degree a thousand-fold 
more intense than that of the fiercest heat we know 
of; if its surface were bound in a cold compared 
with which our arctic frosts would seem like trop- 
ical heat; or even if the most rapid alternation of 
these extremes took place upon and within it; even 
then we could not conclude that the principal pur- 
pose for which the Almighty had created it had not 
been the support of life, either in long-past ages or 
in ages yet to come. And lastly, though we could 
safely assert of any celestial object, that neither now, 
nor at any past or future time, could it serve as the 
abode of living creatures, yet we are led by terres- 
trial analogies to the conclusion that it has yet been 
created to support life in other ways. So that those 
very orbs, of which it seems safest to assert that they 
are, have ever been, and must ever remain uninhab- 
ited, speak to us, no less strongly than those which 
appear best suited for habitation, of the existence of 
other worlds than ours. 



CHAPTER II 

WHAT WE LEARN PROM THE SUN 

I DO not propose to dwell in this chapter on the 
views which have been propounded respecting 
the sun's habitability. It is not merely that I 
regard those views as too bizarre and fanciful to find 
place in a serious consideration of the subject I am 
dealing with, nor that the progress of recent obser- 
vation has rendered them utterly untenable, but that, 
in fact, they do not belong to what the sun teaches 
us. I wish to consider only the real evidence which 
the sun affords respecting the scheme of creation, to 
dwell upon the purposes which he subserves in the 
economy of the solar system, and thence to deduce a 
lesson respecting those other suns scattered through- 
out space, which we call the fixed stars. 

Let us first endeavor to form adequate conceptions 
respecting the dimensions of the great central lumi- 
nary of the solar system. 

Let the reader consider a terrestrial globe three 
inches in diameter, and search out on that globe the 
tiny triangular speck which represents Great Britain. 
(36) 



WHAT WE LEARN FROM THE SUN 



37 



Then let him endeavor to picture the town in which 
he lives as represented by the minutest pin-mark that 
could possibly be made upon this speck. He will 
then have formed some conception, though but an 
inadequate one, of the enormous dimensions of the 
earth's globe, compared with the scene in which his 
daily life is cast. Now, on the same scale, the sun 
would be represented by a globe about twice the 
height of an ordinary sitting-room. A room about 
twenty-six feet in length, and height, and breadth, 
would be required to contain the representation of 
the sun's globe on this scale, while the globe repre- 
senting the earth could be placed in a moderately 
large goblet. 

Such is the body which sways the motions of the 
solar system. The largest of his family, the giant 
Jupiter, though of dimensions which dwarf those of 
the earth or Venus almost to nothingness, would yet 
only be represented by a thirty-two inch globe, on 
the scale which gives to the sun the enormous vol- 
ume I have spoken of. Saturn would have a diam- 
eter of about twenty -eight inches, his ring measuring 
about five feet in its extreme span. Uranus and 
Neptune would be little more than a foot in di- 
ameter, and all the minor planets would be less 
than the three-inch earth. It will thus be seen 
that the sun is a worthy centre of the great scheme 
he sways, even when we merely regard his di- 
mensions. 

The sun outweighs fully seven hundred and forty 
times the combined mass of all the planets which 



38 OTHER WORLDS THAN OURS 

circle around him, so that, when we regard the 
energy of his attraction, we still find him a worthy 
ruler of the planetary scheme. 

But, after all, the enormous volume and mass of 
the sun form the least important of his characteristics 
as the ruling body of the solar system. It is when 
we contemplate him as the source whence the sup- 
plies of heat and light required by our own world 
and the other planets are plentifully bestowed, that 
we see what is his chief office in the economy of 
the planetary scheme. 

Properly speaking, the physical constitution of the 
sun only requires to be dealt with in such a work as 
the present in so far as it is directly associated with 
the sun's action upon the worlds around him, or as 
it may bear on the question of the constitution of 
those worlds. But the subject is so interesting, and 
it would indeed be so difficult to draw a line of 
demarcation between the facts which bear upon the 
question of other worlds and those which do not, 
that I may be permitted to enter at some length into 
a consideration of the solar orb as modern physical 
discoveries present it to our contemplation. 

The study of solar physics may be said to have 
commenced with the discovery of the sun spots, about 
two hundred and sixty years ago. These spots were 
presently found to traverse the solar disk in such a 
way as to indicate that the sun turns upon an axis 
once in about twenty-six days. Nor will this rotation 
appear slow, when we remember that it implies a mo- 
tion of the equatorial parts of the sun's surface at a 



WHAT WE LEARN FROM THE SUN 39 

rate exceeding some seventy times the motion of onr 
swiftest express trains. 

Next came the discovery that the solar spots are 
not surface stains, but deep cavities in the solar sub- 
stance. The changes of appearance presented by the 
spots as they traverse the solar disk led Dr. Wilson 
to form this theory so far back as 1779; but, strangely 
enough, it is only in comparatively recent times that 
the hypothesis has been finally established, since 
even within the last ten years a theory was put for- 
ward which accounted satisfactorily for most of tha 
changes of appearance observed in the spots, by 
supposing them to be due to solar clouds hanging 
suspended at a considerable elevation above the true 
photosphere. 

Sir William Herschel, reasoning from terrestrial 
analogies, was led to look on the spot-cavities as 
apertures through a double layer of clouds. He 
argued that, were the solar photosphere of any other 
nature, it would be past comprehension that vast 
openings should form in it, to remain open for 
months before they close up again. Whether we 
consider the enormous rapidity with which the spots 
form and with which their figure changes, or the 
length of time that many of them remain visible, we 
find ourselves alike perplexed, unless we assume that 
the solar photosphere resembles a bed of clouds. 
Through a stratum of terrestrial clouds openings may 
be formed by atmospheric disturbances, but while 
undisturbed the clouds will retain any form once 
impressed upon them, for a length of time corre- 



40 OTHER WORLDS THAN OURS 

sponding to the weeks and months during which the 
solar spots endure. 

And because the solar spots present two distinct 
varieties of light, the faint penumbra and the dark 
umbra or nucleus, Herschel saw the necessity of as- 
suming that there are two beds of clouds, the outer 
self-luminous and constituting the true solar photo- 
sphere, the inner reflecting the light received from 
the outer layer, and so shielding the real surface of 
the sun from the intense light and heat which it 
would otherwise receive. 

But while recent discoveries have confirmed Sir 
William Herschel 7 s theory about the solar cloud- 
envelopes, they have by no means given counte- 
nance to his view that the body of the sun may 
possibly be cool. The darkness of the nucleus of a 
spot is found, on the contrary, to give proof that in 
that neighborhood the sun is hotter, because it parts 
less readiiy with its heat. We shall see presently 
how this is. Meantime let it be noticed, in passing, 
that a close scrutiny of large solar spots has revealed 
the existence of an intensely black spot in the midst 
of the umbra. This black spot must be regarded as 
the true nucleus. 

The circumstance that the spots appear only on 
two bands of the sun's globe, corresponding to the 
sub-tropical zones on our own earth, led the younger 
Herschel to conclusions as important as those which 
his father had formed. He reasoned, like his father, 
from terrestrial analogies. On our own earth the 
sub-tropical zones are the regions where the great 



'M 



WHAT WE LEARN FROM THE SUN 41 

cyclonic storms have their birth, and rage with their 
chief fury. Here, therefore, we have the analogue of 
the solar spots, if only we can show reason for be- 
lieving that any causes resembling those which gener- 
ate the terrestrial cyclone operate upon those regions 
of the sun where the solar spots make their appear- 
ance. 

We know that the cyclone is due to the excess 
of heat at the earth's equator. It is true that this 
excess of heat is always in operation, whereas cy- 
clones are not perpetually raging in sub tropical cli- 
mates. Ordinarily, therefore, the excess of heat does 
not cause tornadoes. Certain aerial currents are gen- 
erated, whose uniform motion suffices, as a rule, to 
adjust the conditions which the excess of heat at the 
equator would otherwise tend to disturb. But when 
through any cause the uniform action of the aerial 
currents is either interfered with, or is insufficient 
to maintain equilibrium, then cyclonic or whirling 
motions are generated in the disturbed atmosphere, 
and propagated over a wide area of the earth's 
surface. 

How we recognize the reason of the excess of heat 
at the earth's equator, in the fact that the sun shines 
more directly upon that part of the earth than on the 
zones which lie in higher latitudes. Can we find any 
reason for suspecting that the sun, which is not heated 
from without as the earth is, should exhibit a similar 
peculiarity? Sir John Herschel considers that we can. 
If the sun has an atmosphere extending to a consid- 
erable distance from his surface, then there can be 



t 



42 OTHER WORLDS THAN OURS 

little doubt that, owing to his rotation upon his axis, 
this atmosphere would assume the figure of an oblate 
spheroid, and would be deepest over the solar equa- 
tor. Here, then, more of the sun's heat would be 
retained than at the poles, where the atmosphere is 
shallowest. Thus, that excess of heat at the solar 
equator which is necessary to complete the analogy 
between the sun spots and terrestrial cyclones seems 
satisfactorily established. 

It must be remarked, however, that this reason- 
ing, so far as the excess of heat at the sun's equator 
is concerned, only removes the difficulty a step. If 
there were indeed an increased depth of atmosphere 
over the sun's equator sufficing to retain the requisite 
excess of heat, then the amount of heat we receive 
from the sun's equatorial regions ought to be appre- 
ciably less than the amount emitted from the remain* 
ing portions of the solar surface. This is not found 
to be the case, so that either there is no such excess 
of absorption, or else the solar equator gives out 
more heat, in other words, is essentially hotter, than 
the rest of the sun. But this is just the peculiarity 
of which we want the interpretation. 

It may be taken for granted, however, that there 
is an analogy between the sun spots and terrestrial 
cyclonic storms, though as yet we are not very well 
able to understand its nature. 

Then next we come to one of the most interesting 
discoveries ever made respecting the sun — the dis- 
covery that the spots increase and diminish in 
frequency in a periodic manner. We owe this dis- 



WHAT WE LEARN FROM THE SVN 43 

covery to the laborious and systematic observations 
made by Herr Schwabe of Dessau. In these pages 
any account of his work would be out of place. We 
need only dwell upon the result, and upon other dis- 
coveries which have been made by observers who 
have taken up the same work. 

Schwabe found, in the course of about ten and a 
half years, the solar spots pass through a complete 
cycle of changes. They become gradually more and 
more numerous up to a certain maximum, and then 
as gradually diminish. At length the sun's face be* 
comes not only clear of spots, but a certain well* 
marked darkening around the border of his disk 
disappears altogether for a brief season. At this 
time the sun presents a perfectly uniform disk. 
Then gradually the spots return, become more and 
more numerous, and so the cycle of changes is run 
through again. 

The astronomers who have watched the sun from 
the Kew Observatory have found that the process of 
change by which the spots sweep in a sort of "wave 
of increase" over the solar disk is marked by several 
minor variations. As the surface of a great sea wave 
will be traversed by small ripples, so the gradual in« 
crease and diminution in the number of the solar 
spots are characterized by minor gradations of change, 
which are sufficiently well marked to be distinctly 
cognizable. 

There seems every reason for believing that the 
periodic changes thus noticed are due to the influ- 
ence of the planets upon the solar photosphere, 



44 OTHER WORLDS THAN OURS 

though in what way that influence is exerted is not 
at present perfectly clear. Some hare thought that 
the mere attraction of the planets tends to produce 
tides of some sort in the solar envelopes. Then, 
since the height of a tide so produced varies as the 
cube or third power of the distance, it has been 
thought that a planet when in perihelion would 
generate a much larger solar tide than when in 
aphelion. So that, as Jupiter has a period nearly 
equal to the sun-spot period, it has been supposed 
that the attractions of this planet are sufficient to 
account for the great spot period. Venus, Mercury, 
the Earth, and Saturn have, in a similar manner, been 
rendered accountable for the shorter and less dis- 
tinctly marked periods. 

Without denying that the planets may be, and 
probably are, the bodies to whose influence the solar- 
spot periods are to be ascribed, I yet venture to ex- 
press very strong doubts whether the attraction of 
Jupiter is so much greater in perihelion than in 
aphelion as to account for the fact that whereas at 
one season the face of the sun shows many spots, 
at another it is wholly free from them. 1 

However, we are not at present concerned so 
much with the explanation of facts as with the 
facts themselves. "We have to consider rather what 



1 Recently Professor Kirkwood has published a most interesting series 
of inquiries, going far to prove that the real secret of the planetary 
influences lies in the fact that the sun's surface is not uniform, and 
that on a certain solar longitude the planetary influences are more 
effective than elsewhere. 



■ — 



WHAT WE LEARN FROM THE SUN 45 

the sun is and what he does for the solar system, 
than why these things are so. 

Let us note, before passing to other circumstances 
of interest connected with the sun, that the variable 
condition of his photosphere must cause him to 
change in brilliancy as seen from vast distances. If 
Herr Schwabe, for instance, instead of observing the 
sun's spots from his watch-tower at Dessau, could 
have removed himself to a distance so enormous that 
the sun's disk would have been reduced, even in the 
most powerful telescope, to a mere point of light, 
there can be no doubt that the only effect which he 
would have been able to perceive would have been 
a gradual increase and diminution of .brightness, hav- 
ing a period of about ten and a half years. 

Our sun, therefore, viewed from the neighbor- 
hood of any of the stars, whence undoubtedly he 
would simply appear as one among many fixed stars, 
would be a "variable," having a period of ten and 
a half years. And further, if an observer, viewing 
the sun from so enormous a distance, had the means 
of very accurately measuring its light, he would un- 
doubtedly discover that, while the chief variation of 
the sun takes place in a period of ten and a half 
years, its light is subjected to minor variations hav- 
ing shorter periods. 

The discovery that the periodic changes of the 
sun's appearance are associated with the periodic 
changes in the character of the earth's magnetism is / 

the next that we have to consider. \ 

It had long been noticed that, during the course 



( 



46 OTHER WORLDS THAN OURS 

of a single day, the magnetic needle exhibits a 
minute change of direction, taking place in an os- 
cillatory manner. And, when the character of this 
vibration came to be carefully examined, it was 
found to correspond to a sort of effort on the 
needle's part to turn toward the sun. For example, 
when the sun is on the magnetic meridian, the needle 
has its mean position. This happens twice in a day, 
once when the sun is above the horizon and once 
when he is below it. Again, when the sun is mid- 
way between these two positions — which also hap- 
pens twice in the day — the needle has its mean 
position, because the northern and the southern ends 
make equal eiforts (so to speak) to direct themselves 
toward the sun. Four times in the day, then, the 
needle has its mean position, or is directed toward 
the magnetic meridian. But, when the sun is not in 
one of the four positions considered, that end of the 
needle which is nearest to him is slightly turned 
away from its mean position toward him. The 
change of position is very minute, and only the 
exact modes of observation made use of in the pres- 
ent age would have sufficed to reveal it. There it 
is, however, and this minute and seemingly unimpor- 
tant peculiarity has been found to be full of meaning. 
Had science merely measured this minute varia- 
tion, the work would have given striking evidence of 
the exact spirit in which men of our day deal with 
natural phenomena. But science was to do much 
more. The variations of this minute variation were 
to be inquired into; their period was to be searched 



WHAT WE LEARN FROM THE SUN 



47 



for; the laws by which they were regulated and by 
which their period might perhaps itself be rendered 
variable were to be examined; and, finally, their 
relation to other natural laws was to be sought after. 
That Science should set herself to an inquiry so deli- 
cate and so difficult, in a spirit so exacting, was 
nothing unusual. It is thus that all the great dis- 
coveries of our day have been effected. But it is 
well that the reader should recognize the careful 
scrutiny to which natural phenomena have been sub- 
jected before the great laws we have to consider were 
made known. It is thought by many, who have not 
been at the pains to examine what Science is really 
doing in our day, that the wonders she presents to 
men's contemplation, the startling revelations which 
are being made from day to day, are merely dreams 
and fancies, which replace indeed the dreams and fan- 
cies of old times, but have no worthier claims on our 
belief. Those who carefully examine the history of 
science will be forced to adopt a very different opinion. 
The minute vibrations of the magnetic needle, 
thus carefully watched — day after day, month after 
month, year after year — were found to exhibit a yet 
more minute oscillatory change. They waxed and 
waned within narrow limits of variation, but yet in 
a manner there was no mistaking. The period of this 
oscillatory change was not to be determined, how- 
ever, by the observations of a few years. 1 Between 

1 The reader must not understand that the account here given pre- 
sents in any sense even a general view of the labors of those who have 
studied the earth's magnetism. I touch only on those points by which 



a 



48 OTHER WORLDS THAN OURS 

the time when the diurnal vibration was least until 
it had reached its greatest extent, and thence re- 
turned to its first value, no less than ten and a half 
years elapsed, and a much longer time passed before 
the periodic character of the change was satisfactorily 
determined. 

The reader will at once see what these observa- 
tions tend to. The sun spots vary in frequency 
within a period of ten and a half years, and the 
magnetic diurnal vibrations vary within a period of 
the same duration. It might seem fanciful to asso- 
ciate the two periodic series of changes together, and 
doubtless when the idea first occurred to Lamont, it 
was not with any great expectation of finding it con- 
firmed that he examined the evidence bearing on the 
point. Judging from known facts, we may see rea- 
sons for such an expectation in the correspondence 
of the needle's diurnal vibration with the sun's appar- 
ent motion, and the law which has been found to 
associate the annual variations of the magnet's power 
with the sun's distance. But undoubtedly when the 
idea occurred to Lamont it was an exceedingly bold 
one, and the ridicule with which the first announce- 
ment of the supposed law was received, even in 
scientific circles, suffices to show how unexpected 
that relation was which is now so thoroughly estab- 
lished. For a careful comparison between the two 



the association between the earth's magnetism and the physical condi- 
tion of the sun is most clearly indicated; because these points alone 
bear on the subject of this chapter. How they do so will appear 
further on. 



WHAT WE LEARN FROM THE SUN 4tf 

periods has demonstrated that they agree most per- 
fectly, not merely in length, but maximum for max- 
imum, and minimum for minimum. When the sun 
spots are most numerous, then the daily vibration of 
the magnet is most extensive, while, when the sun's 
face is clear of spots, the needle vibrates over its 
smallest diurnal arc. 

Then the intensity of the magnetic action has 
been found to depend upon solar influences. The 
vibrations by which the needle indicates the progress 
of those strange disturbances of the terrestrial mag- 
netism which are known as magnetic storms have 
been found not merely to be most frequent when 
the sun's face is most spotted, but to occur simul- 
taneously with the appearance of signs of disturb- 
ance in the solar photosphere. For instance, during 
the autumn of 1S59, the eminent solar observer, Dar- 
lington, noticed the apparition of a bright spot upon 
the sun's surface. The light of this spot was so 
intense that he imagined the dark glass which pro- 
tected his eye had been broken. By a fortunate 
coincidence, another observer, Mr. Hodgson, hap- 
pened to be watching the sun at the same instant, 
and witnessed the same remarkable appearance. Now 
it was found that the self -registering magnetic instru- 
ments of the Kew Observatory had been sharply dis- 
turbed at the instant when the bright spot was seen. 
And afterward it was learned that the phenomena 
which indicate the progress of a magnetic storm had 
been observed in many places. Telegraphic com- 
munication was interrupted, and, in some cases, tele- 
Soieiioe— 1— 3 



50 OTHER WORLDS THAN OURS 

graphic offices were set on fire; auroras appeared 
both in the northern and southerr hemisphere during 
the night which followed; and the whole frame of 
the earth seemed to thrill responsivelj to the disturb- 
ance which had affected the great central luminary 
of the solar system. 

The reader will now see why I have discussed re- 
lations which hitherto he may perhaps have thought 
very little connected with my subject. He sees that 
there is a bond of sympathy between our earth and 
the sun; that no disturbance can affect the solar 
photosphere without affecting our earth to a greater 
or less degree. But if our earth, then also the other 
planets. Mercury and Venus, so much nearer the 
sun than we are, surely respond even more swiftly 
and more distinctly to the solar magnetic influences. 
But beyond our earth, and beyond the orbit of moon- 
less Mars, the magnetic impulses speed with the ve° 
locity of light. The vast globe of Jupiter is thrilled 
from pole to pole as the magnetic wave rolls in upon 
it; then Saturn feels the shock, and then the vast 
distances beyond which lie Uranus and Neptune are 
swept by the ever-lessening yet ever- widening dis- 
turbance wave. Who shall say what outer planets 
it then seeks? or who, looking back upon the course 
over which it has travelled, shall say that planets 
alone have felt its effects? Meteoric and cometic sys- 
tems have been visited by the great magnetic wave, 
and upon the dispersed members of the one and the 
subtle structure of the other effects even more im- 
portant may have been produced than those striking 



WHAT WE LEARN FROM THE SUN 51 

phenomena which characterize the progress of the 
terrestrial or planetary magnetic storms. 

When we remember that what is true of a rela- 
tively great solar disturbance, such as the one wit- 
nessed by Messrs. Carrmgton and Hodgson, is true 
also (however different in degree) of the magnetic in* 
fiaences which the sun is at every instant exerting, 
we see that a new and most important bond of union 
exists between the members of the solar family. The 
sun not only sways them by the vast attraction of 
his gravity, not only illumines them, not only warms 
them, but he pours forth on all his subtle yet power- 
ful magnetic influences. A new analogy between the 
members of the solar system is thus introduced to re- 
inforce those other analogies which have been held 
so strikingly to indicate that the ends for which our 
earth has been created are not different from those 
which the Creator had in view when He planned the 
other members of the solar system. 1 

And now we pass on to other discoveries, bearing 
at once and with equal force upon the relations be- 
tween the various members of the solar scheme and 



1 I must remark here, once for all, that in speaking of the plans 
of the Creator, of His mode of working, or of the laws which Ke has 
established, I by no means intend such words to be taken literally. 
For want of better, such words as these must be employed in speaking 
of the relations between Almighty God and His universe. But in truth 
these relations are as inconceivable by us as infinity of space or infinity 
of time. We know that they exist, as certainly as we know that space 
and time are both infinite, but human language can no more indicate 
their nature than it can present to the mind an adequate picture c£ 
space or time. 



52 OTHER WORLDS THAN OURS 

upon the position which that scheme occupies in the 
universe. 

Hitherto we have been considering the teachings 
of the telescope; we have now to consider what we 
have learned by means of an instrument of yet higher 
powers. As I shall have to refer very frequently, 
throughout this volume, to the teachings of the spec- 
troscope, it will be well that I should briefly describe 
what it is that this instrument really effects. Were 
I simply to state the results of its use, without de- 
scribing its real character, many of my readers would 
be disposed to believe that astronomers are as credu- 
lous as in reality they are exacting and scrupulous, 
where new facts and observations are in question. 

The real end and aim of the telescope, as applied 
by the astronomer to the examination of the celestial 
objects, is to gather together the light which streams 
from each luminous point throughout space. We 
may regard the space which surrounds us on every 
side as an ocean without bounds or limits, an ocean 
across which there are ever sweeping waves of light, 
either emitted directly from the various bodies sub- 
sisting throughout space, or else reflected from their 
surfaces. Other forms of wave also speed across 
those limitless depths in all directions, but the light* 
waves are those which at present concern us. Our 
earth is as a minute island placed within the ocean 
of space, and to the shores of this tiny isle the light- 
waves bear their message from the orbs which lie 
like other isles amid the fathomless depths around 
us. With the telescope the astronomer gathers to- 



WHAT WE LEARN FROM THE SUN 



58 



gether portions of light-waves which else would have 
travelled in diverging directions. By thus intensify- 
ing their action, he enables the eye to become cog- 
nizant of their true nature. Precisely as the narrow 
channels around our shores cause the lal wave, 
which sweeps across the open ocean in ahajat insen- 
sible undulations, to rise and fall through a wide 
range of variation, so the telescope renders sensible 
the existence of light-waves which would escape the 
notice of the unaided eye. 

The telescope, then, is essentially a lighi-gaiherer. 

The spectroscope is used for another purpose. It 
might be called the light-sifter. It is applied by the 
astronomer to analyze the light which comes to him 
from beyond the ocean of space, and so to enable 
him to learn the character of the orbs from which 
that light proceeds. 

The principle of the instrument is simple, though 
the appliances bj which its full powers can alone be 
educed are somewhat complicated. 

A ray of sunlight falling on a prism of glass or 
crystal does not emerge unchanged in character. Dif- 
ferent portions of the ray are differently bent, so that 
when they emerge from the prism they no longer 
travel side by side as before. The violet part of 
the light is bent most, the red least; the various 
colors from violet through blue, green, and yellow, 
to red being bent gradually less and less. 

The prism then sorts, or sifts, the light-waves, 

But we want the means of sifting the light- waves 
more thoroughly. The reader must bear with me 



54 OTHER WORLDS THAN OURS 

while I describe, as exactly as possible in the brief 
space available to me, the way in which the first 
rough work of the prism has been modified into the 
delicate and significant work of the spectroscope. It 
is well wo li while to form clear views on this point, 
because so many of the wonders of modern science 
are associated with spectroscopic analysis. 

If, through a small round hole in a shutter, light 
is admitted into a darkened room, and a prism be 
placed with its refracting angle downward and hori- 
zontal, a vertical spectrum, having its violet end up- 
permost, will be formed on a screen suitably placed 
to receive it. 

But now let us consider what this spectrum really 
is. If we take the light-waves corresponding to any 
particular color, we know, from optical considera- 
tions, that these waves emerge from the prism in a 
pencil exactly resembling in shape the pencil of white 
light which falls on the prism. They therefore form 
a small circular or oval image on their own proper 
part of the spectrum. Hence the spectrum is in real- 
ity formed of a multitude of overlapping images, 
varying in color from violet to red. It thus appears 
as a rainbow-tinted streak, presenting every gradation 
of color between the utmost limits of visibility at the 
violet and red extremities. 

If we had a square aperture to admit the light, 
we should get a similar result. If the aperture were 
oblong, there would still be overlapping images; but 
if the length of the oblong were horizontal, then, 
since each image would also be a horizontally placed 



1 



WHAT WE LEARN FROM THE SUN 55 

oblong, the overlapping would be less than when the 
images were square. Suppose we diminish the over- 
lapping as much as possible? in other words, suppose 
we make the oblong slit as narrow as possible? Then, 
unless there were in reality an infinite number of im- 
ages distributed all along the spectrum from top to 
bottom, the images might be so narrowed as not to 
overlap; in which case, of course, there would be 
horizontal dark spaces or gaps in our spectrum. Or, 
again, if we failed in finding gaps of this sort by 
simply narrowing the aperture, we might lengthen 
the spectrum by increasing the refracting angle of 
the prism, or by using several prisms, and so on. 
The first great discovery in solar physics, by 
means of the analysis of the prism (though the dis- 
covery had little meaning at the time), consisted in 
the recognition of the fact that, by means of such 
devices as the above, dark gaps or cross-lines can 
be seen in the solar spectrum. In other words, 
light-waves of the various gradations corresponding 
to all the tints of the spectrum from violet to red 
do not travel to us from the great central luminary 
of our system. Eemembering that the effect we call 
color is due to the length of the light-waves, the 
effect of red corresponding to light-waves of the 
greatest length, while the effect of violet corre- 
sponds to the shortest light- waves, we see that in 
effect the sun sends forth to the worlds which circle 
around him light-waves of many different lengths, 
but not of all. Of so complex and interesting a 
nature is ordinary daylight. 



56 OTHER WORLDS THAN OURS 

But spectroscopists sought to interpret these dark 
lines in the solar spectrum, and it was in carrying 
out this inquiry — which even to themselves seemed 
almost hopeless, and to many would appear an utter 
waste of time — that they lighted upon the noblest 
method of research yet revealed to man. 

They examined the spectra of the light from in- 
candescent substances (white-hot metals and the like), 
and found that in these spectra there are no dark 
lines. 

They examined the spectra of the light from the 
stars, and found that these spectra are crossed by 
dark lines resembling those in the solar spectrum, 
but diiferently arranged. 

They tried the spectra of glowing vapors, and 
they obtained a perplexing result. Instead of a 
number of dark lines across a rainbow-tinted streak, 
they found bright lines of various color. Some gases 
would give a few such lines, others many, some only 
one or two. 

Then they tried the spectrum of the electric spark, 
and they found here also a series of bright lines, but 
not always the same series. The spectrum varied ac- 
cording to the substances between which the spark 
was taken, and the medium through which it passed. 

Lastly, they found that the light from an incan- 
descent solid or liquid, when shining through various 
vapors, no longer gives a spectrum without dark lines, 
but that the dark lines which then appear vary in 
position, according to the nature of the vapor through 
which the light has passed. 



WHAT WE LEARN FROM THE SUN 57 

Here were a number of strange facts, seemingly 
too discordant and too perplexing to admit of being 
interpreted. Yet one discovery only was wanting to 
bring them all into unison. 

In 1859, Kirchhoff, while engaged in observing 
the solar spectrum, lighted on the discovery that a 
certain double dark line, which had already been 
found to correspond exactly in position with the 
double bright line forming the spectrum of the glow- 
ing vapor of sodium, was intensified when the light 
of the sun was allowed to pass through that vapor. 
This at once suggested the idea that the presence of 
this dark line (or, rather, pair of dark lines) in the 
spectrum of the sun is due to the existence of the 
vapor of sodium in the solar atmosphere, and that 
this vapor has the power of absorbing the same order 
of light-waves as it emits. It would of course follow 
from this that the other dark lines in the solar spec- 
trum are due to the presence of other absorbent va- 
pors in its atmosphere, and that the identity of these 
would admit of being established in the same way, 
supposing this general law to hold, that a vapor 
emits the same light-waves that it is capable of 
absorbing. 

Kirchhoff was soon able to confirm his views by 
a variety of experiments. The general principles to 
which his researches led — in other words, the prin- 
ciples which form the basis of spectrum analysis — are 
as follows: 

1. An incandescent solid or liquid gives a contin- 
uous spectrum. 



1 



58 OTHER WORLDS THAN OURS 

2. A glowing vapor gives a spectrum of white 
lines, each vapor having its own set of bright lines, 
so that, from the appearance of a bright-line spec- 
trum, one can tell the nature of the vapor or vapors 
whose light forms the spectrum. 

3. An incandescent solid or liquid shining through 
absorbent vapors gives a rainbow-tinted spectrum 
crossed by dark lines, these dark lines having the 
same position as the bright lines belonging to tha 
spectra of the vapors; so that, from the arrange- 
ment of the dark lines in such a spectrum, one can 
tell the nature of the vapor or vapors which sur- 
round the source of light. 1 

The application of the new method of research 

1 To these may be added the following laws: 

4. Light reflected from any opaque body gives the same spectrum 
as it would have given before reflection. 

5. But if the opaque body be surrounded by vapors, the dark Bn98 
corresponding to these vapors make their appearance in the spectrum 
with a distinctness proportioned to the extent to which the light had 
penetrated those vapors before being reflected to us. 

6. If the reflecting body be itself luminous, the spectrum belonging 
to it is superadded to the spectrum belonging to the reflected light. 

7. Glowing vapors surrounding an incandescent source of light may 
cause bright lines or dark lines to appear in the spectrum, according 
as they are more or less heated ; or, they may emit just so much iigh£ 
as to make up for what they absorb, in which case there will remain 
no trace of their presence, 

8. The electric spark presents a bright-line spectrum, compounded 
of the spectra belonging to the vapors of those substances between 
which, and of those through which, the discharge takes place. Ac- 
cording to the nature of these vapors and of the discharge itself, the 
relative intensity of the component parts of the spectrum will be 
variable, 

Lastly, the appearance of the spectrum belonging to any element 
will vary according to the circumstances of pressure and temperature 
under which the element may emit light. 



WHAT WE LEARN FROM THE SUN 



59 



to the study of the solar spectrum quickly led to a 
number of most interesting discoveries. It was found 
that, besides sodium, the sun's atmosphere contains 
the vapors of iron, calcium, magnesium, chromium, 
and other metals. The dark lines corresponding to 
these elements appear unmistakably in the solar 
spectrum. There are other metals, such as copper 
and zinc, which seem to exist in the sun, though 
some of the corresponding dark lines have not yet 
been recognized. As yet it has not been proved that 
gold, silver, mercury, tin, lead, arsenic, antimony, or 
aluminium exist in the sun — though we can by no 
means conclude, nor indeed is it at all probable, that 
they are absent from his substance. The dark lines 
belonging to hydrogen are very well marked indeed 
in solar spectrum, and, as we shall see presently, the 
study of these lines has afforded most interesting in- 
formation respecting the physical constitution of the sun. 
Now we notice at once how importantly these re- 
searches into the sun's structure bear upon the sub- 
ject of this treatise. It would be indeed interesting 
to consider the actual condition of the central orb of 
the planetary scheme, to picture in imagination the 
metallic oceans which exist upon his surface, the 
continual evaporation from those oceans, the forma- 
tion of metallic clouds, and the downpour of metallic 
showers upon the surface of the sun. But apart 
from such considerations, and viewing Kirchhoff's 
discoveries simply in their relation to the subject 
of other worlds, we have enough to occupy our 
attention. 



60 OTHER WORLDS THAN OURS 

If it could have been shown that, in all probabil- 
ity, the substance of the sun consists of materials 
wholly different from those which exist in this earth, 
the conclusion obviously to be drawn from such a 
discovery would be that the ether planets also are 
differently constituted. We could not find any just 
reason for believing that in Jupiter or Mars there 
exist the elements with which we are acquainted, 
when we found that even the central orb of the plan- 
etary system exhibits no such feature of resemblance 
to the earth. But now that we know, quite certainly, 
that the familiar elements, iron, sodium, and calcium, 
exist in the sun's substance, while we are led to 
believe, with almost perfect assurance, that all the 
elements we are acquainted with also exist there, we 
see at once that, in all probability, the other planets 
are constituted in the same way. There may of 
course be special differences: in one planet the pro- 
portionate distribution of the elements may differ, and 
even differ very markedly, from that which prevails 
in some other planet. But the general conclusion re- 
mains, that the planets are formed of the elements 
which have so long been known as terrestrial; for 
we cannot recognize any reason for believing that 
our earth alone, of all the orbs which circle around 
the sun, resembles that great central orb in general 
constitution. 1 



1 It will be seen, in the chapter on Meteors and Comets, that this 
conclusion has a most important bearing on the views we are to form 
respecting the original formation of the planetary scheme. 



WHAT WE LEAEN FROM THE SUN 



61 



Now, we have in this general law a means of 
passing beyond the bounds of the solar system, and 
forming no indistinct conceptions as to the existence 
and character of worlds circling around other suns. 
For it will be seen, in the chapter on the stars, that 
these orbs, like our sun, contain in their substance 
many of the so-called terrestrial elements, while it 
may not unsafely be asserted that all, or nearly all, 
those elements, and few or no elements unknown to 
us, exist in the substance of every single star that 
shines upon us from the celestial concave. Hence we 
conclude that around those suns also there circle orbs 
constituted like themselves, and therefore containing 
the elements with which we are familiar. And the 
mind is immediately led to speculate on the uses 
which those elements are intended to subserve. If 
iron, for example, is present in some noble orb cir- 
cling around Sirius, we speculate not unreasonably 
respecting the existence on that orb — either now or 
in the past, or at some future time— of beings 
capable of applying that metal to the useful pur- 
poses which man makes it subserve. The imagina- 
tion suggests immediately the existence of arts and 
sciences, trades and manufactures, on that distant 
world. We know how intimately the use of iron 
has been associated with the progress of human 
civilization, and though we must ever remain in ig- 
norance of the actual condition of intelligent beings 
in other worlds, we are yet led, by the mere presence 
of an element which is so closely related to the wants 
of man, to believe, with a new confidence, that for 



62 OTh.ER WORLDS THAN OURS 

such beings those worlds must in truth have been 
fashioned. 

I would fain dwell longer on the thoughts sug- 
gested by the researches of Kirchhoff. Gladly too 
would I enter at length on an account of those in- 
teresting discoveries which have been made in con- 
nection with the last two total eclipses of the sun. 
The requirements of space, however, and some doubt 
as to the direct bearing of the last-named discoveries 
on the subject I have in hand, warn me to for- 
bear. One point, however, remains, which is too 
intimately connected with my subject to be passed 
over. 

I refer to the sun's corona. 

It has been proved that the solar prominences con- 
sist of glowing vapors, hydrogen being their chief 
constituent. It has been found also, by comparing 
Mr. Lockyer's observations of the prominence-spectra 
with Dr. Frankland's elaborate researches into the 
peculiarities presented by the spectrum of hydrogen 
at different pressures, that even in the very neigh- 
borhood of the solar photosphere these vapors prob- 
ably exist at a pressure so moderate as to indicate 
that the limits of the sun's vaporous envelope cannot 
lie very far (relatively) from the outer solar cloud- 
layer. 

Now, the solar corona has been seen, during total 
eclipses of the sun, to extend to a distance at least 
equal to the sun's diameter from the eclipsed orb. 
So that, assuming the corona to be a solar atmos- 
phere, it would have a depth of about eight hundred 



WHAT WE LEARN FROM THE SUN 63 

and fifty thousand miles, and being also drawn to- 
ward the sun by his enormous attractive energy (ex- 
ceeding more than twenty-seven times that of the 
earth), it could not fail to exert a pressure on his 
surface exceeding many thousand-fold that of our air 
upon the earth. In fact, such an atmosphere, let its 
outermost layers be as rare as we can conceive, would 
yet have its lower layers absolutely liquefied, if not 
solidified, by the enormous pressure to which they 
would be subjected. We cannot, then, believe this 
corona to be a solar atmosphere. 

Yet it is quite impossible to dissociate the corona, 
either wholly or in part, from the sun. I am aware 
that physicists of eminence have attempted to do 
this, and not only so, but to make of the zodiacal 
light a terrestrial phenomenon. But they have over- 
looked considerations which oppose themselves irre- 
sistibly to such a conclusion. 

In the first place, the mere fact that, during a 
total eclipse, the moon looks black, in the very heart 
of the corona, affords, when properly understood, the 
most conclusive evidence that the light of the corona 
comes from behind the moon. If the glare of our 
atmosphere could by any possibility account for the 
corona (which is not the case), then that glare should 
appear over the moon's disk also. That this is so is 
proved by the fact that, when the glare really does 
cover the moon, as while the sun is but slightly 
eclipsed, the moon is not projected as a black disk 
on the background of the sky, though, where her 
outline crosses the sun, it appears black, by contrast 



d& OTHER WORLDS THAN OURS 

with the intensity of his light. 1 The point seems, 
however, too obvious to need discussion. 

And, secondly, as Mr. Baxendell has pointed 
out, during totality the part of the earth's atmos- 
phere between the eye and the corona is not illu- 
minated by the sun. Over a wide space all round 
the sun we are looking through an atmosphere which 
is completely dark. In fact, if the earth's atmos- 
phere alone were in question, we ought to see a 
dark or negative corona around the sun, the illu- 
minated atmosphere only beginning to be faintly vis- 
ible at a considerable angular distance from the sun. 
This argument, rightly understood, is altogether de- 
cisive of the question. 8 



1 It is also shown most conclusively, by a photograph of the eclipse 
of August, 1868, taken an instant before the totality. Here we see 
the glare trenching upon the moon's disk (elsewhere black), as it 
should theoretically. So soon as totality commenced, the glare had 
reached the moon's limb, whence it must immediately have passed 
quickly away. 

2 In fact, if we take the mode of reasoning by which Mr. Lockyer 
has endeavored to get over certain physical difficulties presently to be 
mentioned, we shall be able to point definitely to the place where his 
argument fails. He says, conceive a tiny moon placed so as to appear 
coincident with the centre of the sun's disk. There will be atmos- 
pheric glare as well as direct sunlight. Now, conceive this small 
moon to expand until it all but covers the sun. Still there will be 
glare and a certain small proportion of direct sunlight. So far his 
reasoning is most just. But when he allows his expanding moon to 
cover the sun, and to extend beyond the solar disk as in total eclipse, 
the atmospheric glare can no longer be assumed to erist all round the 
expanding moon: at the moment when the moon just hides the sun, 
the glare begins to leave the moon, a gradually expanding black ring 
being formed round that body. It is only necessary to consider where 
the glare comes from to see that this must be so. 

I have taken no account of diffraction here, because it has been 



WHAT WE LEARN FROM THE SUN 65 

But the spectroscope Las given certain very per- 
plexing evidence respecting the light of the corona, 
and it remains that we should endeavor to see how 
that evidence bears on the interesting problem which 
the corona presents to our consideration. 

During the total eclipse of last August the Amer- 
ican observers found that the spectrum of the corona 
is continuous, but crossed by certain bright lines. If 
we accept the absence of dark lines as established by 
the evidence (which is doubtful), this result seems at 
first sight very difficult to explain. Eef erring to the 
principles of spectroscopic analysis stated on pp. 57, 
58, it will be seen that we should be led to infer that 
the corona consists of incandescent matter surrounded 
by certain glowing gases. It is difficult to suppose 
that this is the real explanation of the phenomenon. 

Mr. Lockyer suggests that, if the corona shone by 
reflecting the solar light, the continuous spectrum 
might be accounted for by supposing the light from 
the glowing vapors around the sun to supply the part 
wanting where the solar dark lines are, and that some 
of these vapors shining yet more brightly would ex- 
hibit their bright lines upon the continuous back- 
ground of the spectrum. This view, as applied by 
Mr. Lockyer to the theory that the corona is a ter- 
restrial phenomenon, is untenable, for the reasons 
already adduced. But, independently of those rea- 



; 



bundantly proved that no corona of appreciable width could be formed 
around the moon during total eclipse by the diffraction of the rays of 
light as they pass near the moon's limb. 



66 OTHER WORLDS THAN OURS 

sons, there are others which render such a solution 
of the difficulty unavailable. 

Now, remembering that we have two established 
facts for our guidance — (1) the fact that the corona 
cannot be a solar atmosphere, and (2) the fact that 
it must be a solar appendage — I think a way may be 
found toward a satisfactory explanation. 

Let it be premised that the bright lines of the 
coronal spectrum correspond in position to those seen 
in the spectrum of the aurora, and that the same lines 
are seen in the spectrum of the zodiacal light, and in 
that of the phosphorescent light occasionally seen over 
the heavens at right. 

Since we have every reason to believe that the 
light of the aurora is due to electrical discharges 
taking place in the upper regions of the air, we are 
invited to the belief that the coronal light may be 
due to similar discharges taking place between the 
particles (of whatever nature) constituting the corona. 

Now, though the appearance of an aurora is due 
to some special terrestrial action (however excited), 
yet the material substances between which the dis- 
charges take place must be assumed to be at all times 
present in the upper regions of air. In all probabil- 
ity, they are the particles of those meteors which the 
earth is continually encountering. And since we 
know that meteor- systems must be aggregated in far 
greater numbers near the sun than near the earth, we 
may regard the coronal light as due to electrical dis- 
charges excited by the sun's action, and taking place 
between the members of such systems. Besides this 



WHAT WE LEARN FROM THE SUN 67 

light, however, there must necessarily be a large pro- 
portion of light reflected from these meteoric bodies. 
In this way the peculiar character of the coronal 
spectrum may be readily accounted for. We know, 
from the auroral spectrum, that the principal bright 
lines due to the electrical discharges would be pre- 
cisely where we see bright lines in the coronal spec- 
trum. But, besides these, there would be fainter 
bright lines corresponding to the various elements 
which exist in the meteoric masses. These ele- 
ments, we know, are the same as those in the sub- 
stance of the sun. Thus the bright lines would 
correspond in position with the dark lines of the 
solar spectrum. Hence, as light reflected by the 
meteors would give the ordinary solar spectrum, 
there would result from the combination a contin- 
uous spectrum, on which the bright lines first men- 
tioned would be seen, as during the American eclipse. 

What the polariscope has told us respecting the 
corona is in accordance with this view. 

In the same way the quality of the zodiacal light 
admits of being perfectly accounted for, without re- 
sorting to the hypothesis that this phenomenon is a 
terrestrial one. 1 

1 It was with some surprise that, at a late meeting of the Royal 
Astronomical Society, I heard Dr. Balfour Stewart put forward, even 
as a hypothesis, so startling a proposition as this. That the region 
of the counter trades may be at times illuminated by electrical discharges 
will serve to account very well for the occasional phosphorescent appear- 
ance of the whole heavens at night — but the portion of the heavens illumi- 
nated by the zodiacal light has no relation whatever to the atmospheric 
region in which the counter trades prevail. The hypothesis, indeed, is 
wholly untenable. 



■■. 



68 OTHER WORLDS THAN OURS 

The explanation thus put forward has at least 
the advantage of being founded on well-established 
relations. We know that the auroral light is asso- 
ciated with the earth's magnetism, and that meteoric 
bodies are continually falling upon the earth's atmos- 
phere. We know, also, that the sun exerts magnetic 
kiiuences a thousand-fold more intense than those of 
the earth, and that in his neighborhood there must 
be many million times more meteoric systems. 

But we have other and independent reasons, 
which must not be overlooked, for considering the 
corona to be of some such nature as I have sug- 
gested. Leverrier has shown that there probably 
exists in the neighborhood of the sun a family of 
bodies whose united mass suffices appreciably to af- 
fect the motions of the planet Mercury. It would not 
be safe to neglect considerations thus vouched for. 

Mr. Baxendell also, has shown that certain peri- 
odic variations in the earth's magnetism point to the 
existence of such a family of bodies; and he has 
been able to assign to them a position according well 
with that determined by Leverrier. 

Now, whatever opinion we form as to the exact 
character of the system of bodies pointed to by the 
researches of Leverrier and Baxendell— whether we 
suppose that system to form a zone around the sun, 1 

1 I am not here referring to Humboldt's notion that the zodiacal light 
is due to a zone of small bodies round the sun ; a view which only derives 
importance from the fact that Sir John Herschel has been at the pains to 
contradict it. It need hardly be said that Sir John Herschel's opinion has 
a weight which is altogether wanting to Humboldt's, so far as astronomical 
matters are concerned. 



WHAT WE LEARN FROM THE SUN 69 

or that (as I believe) the system is merely due to 
the aggregation of meteoric perihelia in the sun's 
neighborhood — we may be quite certain of this, that 
during a total solar eclipse the system could not fail 
to become visible. Hence there is a double objec- 
tion to the view put forward by Mr. Lockyer and 
others. In the first place, it fails to account for the 
appearance presented by the corona; in the second 
place, it fails to render an account of the implied 
non-appearance of the system which, according to the 
researches of Leverrier and Baxendell, circles around 
the sun. 

It will be seen, in the chapter on " Meteors and 
Comets," how important a bearing these views re- 
specting the nature of the corona have upon the his- 
tory of the solar system. It has been partly for this 
reason that I have here briefly considered the mat- 
ter; but there is another and a most important rela- 
tion in which these views must be regarded. 

We know that the sun is the sole source whence 
light and heat are plentifully supplied to the worlds 
which circle around him. The question immediately 
suggests itself — Whence does the sun derive those 
amazing stores of force from whence he is continually 
supplying his dependent worlds? We know that, 
were the sun a mass of burning matter, he would be 
consumed in a few thousand years. We know that, 
were he simply a heated body, radiating light and 
heat continually into space, he would in like manner 
have exhausted all his energies in a few thousand 
years — a mere day in the history of his system. 



70 OTHER WORLDS THAN OURS 

Whence, then, comes the enormous supply of force 
which he has afforded for millions on millions of 
years, and which also our reason tells us he will 
continue to afford while the worlds which circle 
around him have need of it— in other words, for 
countless ages yet to come? 

iNow, there are two ways in which the solar ener- 
gies might be maintained. The mere contraction o! 
the solar substance, Helmholtz tells us, would suffice 
to supply such enormous quantities of heat that, if 
the heat actually given out by the sun were due to 
this cause alone, there would not, in many thousands 
of years, be any perceptible diminution of the sun's 
diameter. But, secondly, the continual downfall of 
meteors upon the sun would cause an emission of 
heat in quantities vast enough for the wants of all 
the worlds circling round him; while Mb increase 
of mass from this cause would not be rendered per* 
ceptible in thousands of years, either by any change 
in his apparent size or by changes in the motions of 
his family of worlds. 3 

It seems far from unlikely that both these proe* 
esses are in operation at the same time. Certainly 
the latter is, for we know, from the motions of the 



1 Altogether undue stress has been laid upon the probable change ia 
the length of the year, owing to the downfall of meteors upon the sun's 
mass. It is forgotten that the crowded meteors forming the solar corona 
are already within the earth's orbit, and therefore ai ready produce their 
full effect on the length of the year. The subsidence of all these bodies 
at once upon the sun would not affect the length of the year, though it 
would lead to certain modifications In the secular perturbations of the 
earth's orbit in figure and position. 



WHAT WE LEARN FROM THE SVN 71 

meteoric bodies which reach the earth, that myriads 
of these bodies must continually fall upon the sun. 
And if the corona and zodiacal light really be due 
to the existence of flights of meteoric systems cir- 
cling around the sun, or to the existence in his 
neighborhood of the perihelia of many meteoric sys- 
tems, then there must be a supply of light and heat 
from this source, very nearly if not quite sufficient 
to account for the whole solar emission. 

It is well worthy of notice, too, that the associa- 
tion between meteors and comets has an important 
bearing on this question. We know that the most 
remarkable characteristic of comets is the enormous 
diffusion of their substance. Now, in this diffusion 
there resides an enormous fund of force. The con- 
traction of a large comet to dimensions corresponding 
to a very moderate mean density would be accom- 
panied by the emission of a vast supply of heat. 
And the question is worth inquiring into, whether 
we can indeed assume that the meteors which reach 
our atmosphere are solid bodies, and not rather of 
cometic diffusion; since it is difficult otherwise to 
account for the light and heat which they emit. 
Friction through the rarer upper strata of our atmos« 
phere will certainly not account for these phenomenal 
nor, I think, will the compression of the atmosphere 
in front of the meteors; on the other hand, the sud- 
den contraction of a diffused vapor would be accom- 
panied by precisely such results. But, be this as it 
may, it is certain that a large portion of the sub- 
stance of every comet is in a singularly diffused 



72 OTHER WORLDS THAN OURS 

state. And since the meteoric systems circling in 
countless millions round the sun are, in all prob- 
ability, associated in the most intimate manner with 
comets, we may recognise in this diffusion, as well 
as in the mere downfall of meteors, the source of an 
enormous supply of light and heat. 

And lastly, turning from our sun to the other 
suns which shine in uncounted myriads throughout 
space, we see the same processes at work upon them 
all. Each star-sun has its coronal and its zodiacal 
disks, formed by meteoric and cometic systems; for 
otherwise each would quickly cease to be a sun. 
Each star-sun emits, no doubt, the same magnetic in- 
fluences which give to the zodiacal light and to the 
solar corona their peculiar characteristics. And thus 
the worlds which circle round those orbs may resem- 
ble our own in all those relations which we refer to 
terrestrial magnetism, as well as in the circumstance 
that on them also there must be, as on our own 
earth, a continual downfall of minute meteors. In 
those worlds, perchance, the magnetic compass directs 
the traveller over desert wastes or trackless oceans; 
in their skies, the aurora displays its brilliant stream- 
ers; while, amid the constellations which deck their 
heavens, meteors sweep suddenly into view, and com- 
ets extend their vast length athwart the celestial 
vault, a terror to millions, but a subject of study 
and research to the thoughtful. 



CHAPTEE in 



THE INFERIOR PLANETS 



IN considering the habitability of various portions 
of the solar system, we have to draw a marked 
distinction between the planets which travel 
within the orbit of the earth and those which lie 
beyond its range. So far, indeed, as our belief in 
these orbs being inhabited is concerned, we may ap- 
ply the same processes of reasoning to one set of 
planets as to the other. Until it has been demon- 
strated that no form of life can exist upon a planet, 
the presumption must be that the planet is inhab- 
ited. But it is impossible to contemplate the various 
members of our solar system, without being led to 
consider their physical habitudes rather with rela- 
tion to the wants of such creatures as exist upon our 
own earth, than merely with reference to the exist- 
ence of life of some sort upon their surface. View- 
ing Venus and Mercury in this way, we have a dif- 
ferent set of relations to deal with than we find 
among the outer planets. We are struck, at once, 
with the marked effects which seem associable with 

their comparative proximity to the sun's orb. This 
Science— 1—4 (73) 



74 OTHER WORLDS THAN OURS 

feature and the shortness of their period of revo- 
lution — that is, of their year — are the characteristic 
peculiarities we have to deal with. 

I would willingly pay some attention here to the 
story of Vulcan, the planet which has been supposed 
to circle yet more closely than Mercury around the 
centre of our system, were it not for the great doubt 
in which the existence of this planet seems en- 
shrouded. If, on the one hand, we have the evi- 
dence of Lescarbault that, on a certain day, and at a 
certain hour, he saw a dark object, round like 
a planet, crossing the face of the sun, we have also 
the evidence of Liais, whose name is much better 
known among astronomers, that at that very hour 
there was no such object on the solar disk. There 
is nothing to render the existence of an intra-Mer- 
curial planet at all unlikely; and there are many 
observations which scarcely seem explicable on any 
other hypothesis. Still, as yet we have not that 
clear and unmistakable evidence which would permit 
me to speak of Vulcan as a planet known to astron- 
omers, and I wish, while within the bounds of the 
solar system, to limit myself to the consideration of 
bodies which have been recognized and examined. 

Mercury circles around the sun in the brief period 
of eighty-eight days, or rather less than three of our 
months. So that, if the planet has seasons, these 
must be severally about three weeks long. His dis- 
tance from the sun varies between somewhat wide 
limits, owing to the eccentricity of his orbit. When 
he is nearest to the sun, he receives ten and a half 



THE INFERIOR PLANETS 75 

times more light and heat from that luminary than 
we do; but, when he removes to his greatest dis- 
tance, the light and heat he receives are reduced by 
more than one-half. Even then, however, the sun 
blazes in the skies of Mercury with a disk four and 
a half times larger than that which he presents to 
the observer on earth. 

Undoubtedly these peculiarities, the shortness of 
the Mercurial year, and the immense amount of light 
and heat poured by the sun upon the planet, are cir- 
cumstances which do not encourage, at first sight, the 
belief that any creatures can subsist upon this planet 
resembling those with which we are familiar. We 
see, at once, that all forms of vegetation in Mercury 
must differ in a very striking manner from those 
which exist upon the earth, because their structure 
has to be adapted to much more rapid changes of 
temperature. And the existence of a totally distinct 
flora suggests at once the belief that animal life on 
Mercury must be very different from what we see 
around us. 

Let us, however, proceed a few steps further. 

It has been found that Mercury rotates upon his 
axis, and, if we may put faith in the observations of 
Schroter, the Mercurial day is only a few minutes 
longer than our own. But, though the fact of the 
planet's rotation has been observed, it has not been 
found possible to determine in what position the axis 
of rotation lies. It has been said that the planet's 
equator is much more inclined than the earth's to 
the plane in which the planet travels; but little re- 



76 OTHER WORLDS THAN OURS 

liance can be placed on the evidence which has been 
adduced in favor of this view. 

We are thus left altogether in doubt as to the 
nature of the Mercurial seasons. That the planet has 
seasons of some sort we are certain, because, even is 
the axis were so placed that perpetual spring reigned 
upon the planet — I mean, that the days and nights 
were at all times and in all places equal — yet his 
varying distance from the sun would give changes 
of temperature quite as marked as those which char- 
acterize our seasons in England, and very much more 
marked than those known in tropical regions. Of 
course, if this is the actual arrangement, there are 
different climates in different parts of the planet. 
Near his poles, the sun, though visible for half the 
Mercurial day, attains yet but a low elevation above 
the horizon; just as he does on a spring day within 
our own polar circles. At the equator the sun passes 
day after day to the zenith, and pours down upon 
the planet an amount of light and heat far exceeding 
the light and heat of our tropical climates. A sun 
immediately overhead, and showing a diameter vary- 
ing from more than twice to more than three times 
that of our sun, must be a noble, and may be a ter- 
rible, phenomenon in the skies of Mercury. 

There is yet another arrangement by which, to 
a portion of the planet, at any rate, the Mercurial 
seasons might be tempered. If his axis is so placed 
that what would be the winter season, were his orbit 
not eccentric, takes place, for one hemisphere, when 
the planet is nearest to the sun, then undoubtedly it 



THE INFERIOR PLANETS 



77 



may very well happen (the inclination of his axis 
being suitably adjusted) that this so-called winter 
season is the warmest part of the year for that 
hemisphere. In this case there would be the least 
possible violence in the succession of the Mercu- 
rial seasons for that hemisphere. But in the other 
hemisphere the seasonal changes would be corre- 
spondingly intensified. 

In either of these cases it is readily conceivable 
that even forms of life resembling those we are ac- 
quainted with on earth might exist on Mercury, and 
that without any special provision for tempering the 
great heat and light of the sun. Those regions which 
correspond to our temperate and tropical zones would 
indeed scarcely be habitable; but the polar regions 
of the planet would not form a disagreeable abode. 

If, however, the equator of the planet is very 
much inclined to the plane in which Mercury travels, 
it cannot be doubted that no form of life known upon 
earth can possibly exist upon Mercury, without some 
special arrangements for tempering the seasonal 
changes. This will appear when we come to deal 
with the effect of the great inclination which some 
astronomers have ascribed to the equator of Venus, 
and therefore we need not consider the relation with 
regard to Mercury, of whose axial inclination no trust- 
worthy information has hitherto been obtained. 

It remains for us to consider what sort of provis- 
ion may have been ^made to temper the great heat 
poured by the sun upon Mercury. 

The climate of a planet, considered generally, is 



r8 OTHER WORLDS THAN OURS 

largely influenced by the nature of the planet's atmos- 
phere. We have very clear evidence on this point, 
in the effects which we notice on our own earth. If 
we ascend to the summit of a lofty mountain, we 
find the air much colder than at its base. In India, 
though the full heat of a tropical sun is poured day 
after day upon the snowy summits of the Himalayas, 
yet the air continues colder than in the bitterest mid- 
winter weather experienced by us in England. Not 
that the solar rays have no power. The heat is, in 
reality, even greater than on the plains, because it 
has not been intercepted by vapor- laden air. But 
the air itself is not heated. Owing to its extreme 
rarity and dryness, it neither impedes the passage 
of the sun's heat to the earth, nor prevents the re- 
turn of that heat from the earth by radiation or 
reflection; and this very fact, that it does not impede 
the passage of heat, means nothing else than that the 
air does not become heated. 1 

We have, then, so far as a rare atmosphere is con- 
cerned, two points to dwell upon — the readiness with 



1 The following passage, quoted by Professor Tyndall from Hooker's 
"Himalayan Journals," illustrates the peculiarities referred to above: 
"At 10,000 feet, in December, at 9 a.m., I saw the mercury mount 
to 132°, while the temperature of shaded snow hardly was 22°. At 
13,100 feet, in" January, at 9 a.m., it has stood at 98°, with a differ- 
ence of 68.2°, and at 10 A.M at 114°, with a difference of 81.4°, while 
the radiating thermometer on the snow had fallen at sunrise to 0.7°." 
Such observations as these are well worth studying. It is interesting 
to consider that at the summit of the highest peaks of the Himalayas 
the midday heat of the sun must sometimes be near, if not above, the 
boiling point corresponding to those places, since water would boil on 
Mount Everest at a temperature of little more than 160°. 



THE INFERIOR PLANETS 



79 



which such an atmosphere permits the sun's heat to 
reach the surface of a planet, and the readiness with 
which it permits the planet's heat to pass away into 
space. Now, we might feel doubtful which of these 
two effects was chiefly to be regarded, were it not that 
on our own earth we have experience of the effects 
of a very rare atmosphere. We know that the 
climate of very elevated regions is relatively much 
cooler than that of places on the plain. Thus we 
learn that the direct heating powers of the sun 
are not so much to be considered, in judging of 
the climate of any region, as the quality of the 
atmosphere. 

Yet we must not deceive ourselves by inferring 
that mere rarity of atmosphere can compensate fully 
for an increased intensity of solar heat. It is not 
true that the climate of a place on the slopes of the 
Andes or the Himalayas corresponds to that of a re- 
gion on the plain which has an atmosphere equally 
warm. The circumstances are, in fact, wholly differ- 
ent. On the plain there is, it is true, the same 
amount of heat in the case supposed: but the air 
is denser and more moisture -laden; the nights are 
warmer because the skies are less clear and the heat 
escaping from the earth is intercepted by clouds or 
by the transparent aqueous vapor in the air; and, 
lastly, there is not so great a contrast between the 
warmth of the air and the direct heat of the solar 
rays. 

If the atmosphere of Mercury, therefore, be excess- 
ively rare, as some have supposed, so as to afford 



80 OTHER WORLDS THAN OURS 

an Alpine or Himalayan climate in comparison with 
the tremendous heat we should otherwise ascribe to 
the climate of the planet, there would by no means 
result a state of things resembling that with which 
we are familiar on earth. We must not, in our 
anxiety to people Mercury with creatures such as we 
know of, blind ourselves to the difficulties which have 
to be encountered. We cannot thin the Mercurial air, 
without adding to the direct effects of the sun upon 
the Mercurial inhabitants. Whether in this way we 
increase the habitability of the planet may be doubted 
when we consider that the direct action of the sun's 
rays upon the tropical regions of Mercury, thus de- 
prived of atmospheric protection, would produce a 
heat four or five times greater than that of boiling 
water. It will hardly be thought that the intense 
cold in the shade, or during the Mercurial night, 
would compensate for so terrible a heat. In fact, 
this view of the Mercurial climate would lead us to 
find a close resemblance between the inhabitants of 
the planet and the unfortunates described by Dante 
as doomed 

"A sofferir torment! e caldi e gieli." 

It would seem hard to believe in the existence of 
any organized forms under such conditions, unless 
perhaps such " microscopic creatures, with siliceous 
coverings, ,, as Whewell proposed to people Venus 
with. 

However, we have yet to consider whether an 
atmosphere of a different sort might not be better 



THE INFERIOR PLANETS 8l 

suited to the requirements of Mercury. We have 
seen the effects of a rare atmosphere, let us inquire 
into those which might be ascribed to a dense one. 
The ordinary effect of a dense atmosphere we 
know to be an increase of heat, which is certainly 
not what we require in the case of Mercury. Nor 
are we familiar with any region upon our earth in 
which a dense atmosphere produces a contrary climatic 
effect; so that we have no analogy to support us in 
the belief that, possibly, a dense atmosphere might, 
under particular circumstances, serve to guard a 
planet from the solar rays. It seems possible, how- 
ever, that an atmosphere might be so constituted as 
to remain almost constantly loaded with heavy cloud- 
masses. In this case, it by no means follows that 
such effects would follow as we ordinarily associate 
with a moisture -laden atmosphere. Up to a certain 
point, doubtless, the increase of moisture in the air 
tends to an increase of warmth; because the aqueous 
vapor exercises a greater effect in preventing the 
escape of heat from the earth than in guarding the 
earth from the solar rays. And, as I have said, 
the only climatic effect we can associate with the fre- 
quent presence of large quantities of aqueous vapor 
in the air, or therefore with an ordinarily clouded 
state of the sky, is that of a general increase of 
heat. But, just as we know that a cloudy day is 
not necessarily nor even commonly a warm day, it 
may well be that an atmosphere so dense as to be at 
all times cloud-laden serves as a protection from the 
sun's intense heat. So that, instead of assigning dense 



82 OTHER WORLDS THAN OURS 

atmospheres exclusively to the more distant planets, 
as some astronomers have done, we might be led to 
see in an envelope of great density the means of de- 
fending the inhabitants of Mercury and Venus from 
the otherwise unendurable rays of their near neigh- 
bor, the sun. 

Although Mercury is not a planet which can be 
satisfactorily examined with the telescope, yet, so 
far as can be judged from his aspect, his atmosphere 
is in reality much denser than our earth's, and 
loaded with cloud-masses of enormous extent. Still 
the evidence on these points is far from satisfactory; 
and there is one peculiarity of the planet which does 
not accord with this view of the constitution of his 
atmosphere. Undoubtedly, if the light we receive 
from Mercury came from a cloudy envelope, it would 
be more brilliant than the light we should receive 
from the surface of continents and oceans. In fact, 
the most brilliant light we could receive from a 
globe of a given size, placed at a given distance 
from the sun, would be that which would be re- 
flected were such a globe covered with clouds. Now, 
there can be no doubt whatever that Mercury does 
not reflect the same proportion of light from his sur- 
face that some of the planets do. He would be, 
when favorably situated, the brightest of all the 
planets were this so; 1 though, seen as he always is, 



1 Placing Mercury in perihelion and at his elongation, we get a half 
disk, the planet about 90,000,000 miles from us, and about 30,000,000 
from the sun, his diameter about 3,000 miles. Now, if we wish to com- 
pare the light he then sends us with that of Jupiter at his brightest, on 



THE INFERIOR PLANETS 83 

on the bright background of a full twilight sky, he 
would not make so striking an appearance as Jupiter 
does when in opposition. This, however, is not the 
case. I remember being much struck by the superior 
light of Jupiter, on the afternoon of February 23, 
1868, when the two planets were very close together, 
Mercury being nearly at his brightest, whereas Ju- 
piter, then near conjunction, was considerably less 
bright than when in opposition. Yenus was close 
by, and outshone both Mercury and Jupiter. 

It seems difficult, therefore, to believe that the 
light of Mercury comes from a cloudy envelope. But 
there is still one supposition which may restore our 
belief in the habitability of the planet by creatures 
not very different from those which inhabit our 
earth. If it has a double cloud-envelope, the upper 
like our cirrus clouds, less compact than the lower, 
and permitting a portion of the sunlight to pass 
through, it is possible that the lower cloud-layer 
would be seen partly in shadow. I must admit that 
the explanation is not quite satisfactory, because, 



the assumption of equal reflective powers, we must take Jupiter at a dis- 
tance of about 360,000,000 miles from us, and about 450,000,000 miles from 
the sun, showing a full disk, his diameter about 90,000 miles (I put all the 
numbers round, for convenience of calculation). We find, then, that the 
ratio of Mercury's light to Jupiter's is 

1 (3, 000) 2 . (90, OOP) 2 

2 (90,000,000) 2 X (30,000,000) 2 S (360,000,©00) 2 X (450,000,000) 2 
or £ (4) 2 (15)2 : (30) 2 , or exactly 2 to 1. 

The observation above cited is sufficient to prove that a very different state 
of things actually prevails ; in other words, that the reflective powers of the 
two planets are very different. Unless, indeed, Jupiter shines in part by 
inherent light. 



84 OTHER WORLDS THAN OURS 

just as much light as the outer clouds intercepted 
they would reflect; still, it is conceivable that the 
usual arrangement of these clouds may be such, that 
to us, who do not look at the planet in the direction 
in which the sun's rays fall, but somewhat aslant, 
the shadows of the upper clouds upon the dense and 
compact lower envelope may be rendered in large 
part visible. 

After all, the reader may prefer the view which 
recognizes in the polar regions of Mercury places 
suitable for organic existences, while the equatorial 
and neighboring regions are zones of fire, whose dan- 
gers the bravest Mercurials, the very Livingstones 
upon that planet, would not dare to face. We may 
picture to ourselves, on this view, the various con- 
trivances by which the inhabitants of the two polar 
(that is, in reality, temperate) circles manage to com- 
municate. There may be regions where favoring 
circumstances narrow the uninhabitable zone so much 
that the inhabitants of one polar circle may travel to 
the other (or, at least, cross the most dangerous por- 
tion of the hot zone) in the course of the Mercurial 
night. Or perhaps tunnels may be run, or sheltered 
cuttings made, along which the voyage may be made 
in comparative safety. Ocean communication there 
can be none, if the Mercurial skies are clear, since 
the sun's heat on the tropical zone would suffice to 
boil away any water which might find its way there. 

Certainly, the smallness of the planet and the 
diminished effects of gravity upon its surface would 
tend to make communication much easier, and the 



THE INFERIOR PLANETS 



85 



construction of protective tunnels or cuttings a com- 
paratively light task. What the exact force of grav- 
ity at the surface of Mercury may be we do not 
know, because our means of determining the mass of 
the planet are not so satisfactory as in the case 
of the other primary members of the solar system. 
If Mercury had a satellite we could tell his weight 
at once. If he were as large as Venus we could tell 
his weight by observing his effect in disturbing the 
motions of that planet. As it is, the only means we 
have of weighing Mercury is the observation of his 
effect in disturbing any comet which may pass near 
him. In this way the planet has been weighed, but 
the balance thus employed is not a satisfactory one 
altogether, because we are not quite certain how 
much of the disturbance of a comet when near Mer- 
cury is due to the planet's attraction. Formerly it 
was supposed that the mean density of Mercury was 
equal to that of lead; but, from the perturbations of 
Encke's comet in Mercury's neighborhood, astron- 
omers have been led to the conclusion that the den- 
sity of the planet is not more than one -sixth greater 
than our earth's. It follows that, as his diameter is 
little more than three thousand miles, our earth 
is about fifteen times as heavy as Mercury. Gravity 
at his surface is such that a pound weight of ours 
would weigh rather less than seven ounces on Mer- 
cury. Hence the creatures which seem to us most 
unwieldy — the elephant, the hippopotamus, and the 
rhinoceros, or even those vast monsters, the mam- 
moth, the mastodon, and the megatherium, which 



86 OTHER WORLDS THAN OURS 

bore sway over our globe in far-off eras — might emu- 
late on Mercury the agility of the antelope or the 
greyhound. 

There can be no doubt that, where gravity acts 
so feebly, all engineering operations would be ren- 
dered very much simpler — bridges could have a 
wider span and yet be stronger than our terrestrial 
ones, buildings could be loftier and yet be raised 
more easily, and transit of all sorts would be effected 
much more readily, while at the same time the dis- 
tances to be traversed are very much less than on 
our earth, since the surface of Mercury is little more 
than one-seventh of the earth's. 

The peculiarities which characterize Yenus are for 
the most part similar in kind to those we have had 
to consider in the case of Mercury. But at the out- 
set of our inquiries into the physical habitudes of 
this most beautiful planet, we must point to the 
striking resemblance which it bears, in some re- 
spects, to our own earth. So far, indeed, as tele- 
scopic and physical researches have yet led us, the 
planet Mars, as we shall presently see, appears to 
exhibit habitudes more closely corresponding to those 
we are apt to consider essential to the wants of liv- 
ing creatures. But in size, in situation, and in den- 
sity, in the length of her seasons and of her rotation, 
in the figure of her orbit and in the amount of light 
and heat she receives from the sun, Yenus bears a 
more striking resemblance to the earth than any orb 
within the solar system. In fact, there is no other 
pair of planets between which so many analogies can 



THE INFERIOR PLANETS 



87 



be traced as between Yen us and the earth. Uranus 
and Neptune are similar in many respects, but they 
differ in at least as many. Jupiter and Saturn are, 
in a sense, the brother giants of the solar scheme, 
while the dwarf orbs Mars and Mercury present 
many striking points of similarity; but between 
neither of these pairs can we trace so many feat- 
ures of resemblance as those which characterize 
the twin planets Venus and Terra, while the feat- 
ures of dissimilarity in either pair are perhaps 
even more obvious than the points of resemblance. 
Had Yenus but a moon as the earth has, we 
might doubt whether, in the whole universe, two 
orbs exist which are so strikingly similar to each 
other. 

And here we may pause for a moment to consider 
one of the most perplexing enigmas that has ever 
been presented to astronomers. Are we indeed cer- 
tain that Yenus has no moon? The question seems 
a strange one, when it is remembered that year after 
year Yenus has been examined by the most eminent 
modern observers, armed with telescopes of the most 
exquisite denning power, without any trace of a com- 
panion orb being noticed. Nor, indeed, can any 
reasonable doubts be entertained respecting the 
moonless condition of Yenus, by those who appre- 
ciate the character of modern telescopic observations; 
and yet, if I had begun this paragraph by stating 
the evidence in favor of the existence of a satellite, 
I believe that nearly every reader would have come 
to the conclusion that most certainly the Planet of 



88 OTHER WORLDS THAN OURS 

Love has an attendant orb. They are not amateur 
observers only who have seen a moon attending on 
Venus, but such astronomers as Cassini and Short, 
the latter with two different telescopes and four dif- 
ferent eye-pieces. Four times, between May 3 and 
11, 1761, Montaigne saw a body near Yenus, which 
presented a phase similar to that of the planet, pre- 
cisely as a satellite would have done. From these 
observations M. Baudouin deduced for the new star 
a diameter of about two thousand miles, and a dis- 
tance from Yenus nearly equal to that which sepa- 
rates the moon from the earth. In March, 1764, 
again, Bodkier saw the enigmatical companion; Hor- 
rebow saw it a few days later; and Montbaron saw 
it in varying positions on March 15, 28, and 29. 
Lastly, Scheuten, who witnessed the transit of Yenus 
in 1761, declares that he saw a satellite accompany 
Yenus across the face of the sun. So that we cannot 
be greatly surprised that even so skilful an observer 
as the late Admiral Smyth was disposed to believe 
in the existence of a satellite of Yenus. "The con- 
tested satellite is, perhaps," he remarked, "extremely 
minute, while some parts of its body may be less 
capable of reflecting light than others; and when the 
splendor of its primary and our inconvenient station 
for watching it are considered, it must be conceded 
that, however slight the hope may be, the search 
ought not to be relinquished." 

There is little occasion to dwell upon Yenus' s 
moonless condition, because the inferior planets are 
much less affected by the want of a moon than a 



THE INFERIOR PLANETS 89 

superior planet would be. The service rendered by 
our own moon, as a luminary of the night, is the 
least important work she does in our behalf. It is 
as the chief regulator of the tides that the moon be- 
friends us most usefully. Now, Venus has no need 
of lunar tides. Assuming that she has oceans such 
as those which exist upon the earth, her solar tides 
must be about two and a half times as high as the 
solar tides raised in our own oceans. And since our 
lunar tidal wave is about two and a half times as 
high as the solar one, we have tides ranging between 
the highest spring tides, which are three and a half 
times as high as the solar tide alone, and the lowest 
neap tides, which are only one and a half times as 
high as the solar wave. Venus has constant tides, 
therefore, corresponding very closely to the mean 
tides on our own earth; and therefore perfectly well 
adapted to subserve all the purposes which our tides 
render us, only with less variety in their mode of 
operation. Mercury also has sufficiently high solar 
tides, supposing he has extensive oceans (which may 
reasonably be questioned), since the smallness of 
his dimensions, tending of course to diminish the 
difference of action on which the sun's tidal influence 
depends, is fully compensated by his great proximity 
to that orb. 

Venus has a year of two hundred and twenty -four 
days, seventeen hours, very nearly, and her distance 
from the sun, which varies little during the course 
of a year, is somewhat less than three-fourths of 
that which separates the sun from us. Her day is 



-ssr 



90 OTHER WORLDS THAN OURS 

about thirty-five minutes shorter than ours, and her 
globe somewhat smaller than the earth's. 

It is clear that, merely in the greater proximity of 
Venus to the sun, there is little to render at least 
the larger proportion of her surface uninhabitable by 
such beings as exist upon our earth. The sun, as 
seen in her skies, has a diameter one -third larger 
than he presents to us; and his apparent surface- 
dimensions, on which, of course, his heating and 
illuminating powers depend, are greater in the pro- 
portion of about sixteen to nine. This undoubtedly 
would render his heat almost unbearable in the 
equatorial regions of Venus, but in her temperate and 
subarctic regions a climate which we should find 
well suited to our requirements might very well ex- 
ist; while her polar regions might correspond to our 
temperate zones, and be the abode of the most active 
and enterprising races existing upon her surface. 

Here, however, we have been supposing that Venus 
has seasons resembling our own in character — in other 
words, that her axis of rotation is inclined at about 
the same angle to the plane in which she travels. 
Observations have been made, according to which a 
very different state of things would appear to prevail. 
It has been said, on the authority of observers of some 
eminence, that her axis is inclined only 15° to the 
plane of her orbit. 1 If this is really the case, a 



1 Why is it that, in so many works of popular astronomy, the mis- 
take is made of giving the inclination of a planet's equator to the orbit 
as the inclination of the axis to that plane? In nine out of ten astro- 



THE INFERIOR PLANETS 



91 



number of singular and somewhat complicated rela- 
tions are presented, the result of which it may be in- 
teresting to exhibit to the reader — especially as there 
is very little doubt that in the case of Uranus an 
axial peculiarity of this sort actually exists. 1 

In the first place, the arctic regions of Yenus ex- 
pend within fifteen degrees of her equator (if the 
axis is really bowed as supposed), while the tropics 
extend within fifteen degrees of her poles — so that 
two zones, larger by far than the temperate zones of 
our earth, belong both to her arctic and to her tropi- 
cal regions. It is difficult to say whether her equa- 
torial, her polar, or her arctico-tropical regions would 
be, to our ideas, the least pleasing portion of her 
globe. 

An inhabitant of the regions near either pole has 
to endure extremes of heat and cold, such as would 
suffice to destroy nearly every race of living beings 
subsisting upon the earth. During the summer the 
sun circles continually close to the point overhead, so 
that, day after day, he pours down his rays with an 
intensity of heat and of light exceeding nearly two- 
fold the midday light and heat of our own tropical 
sun. Only for a short time, in autumn and in spring, 
does the sun rise and set in these regions. A spring 



nomical works, the inclination of the earth's axis to her orbit is given 
as 23-£°; were this the case, the larger part of the earth would be un- 
inhabitable. 

1 If the observations of De Tico may be trusted, the inclination of 
Venus, though less than 75°, is still so considerable (about 55°) as to 
justify the general conclusions deduced in the following paragraphs. 



•asp- 



92 OTHER WORLDS THAN OURS 

or autumn day, like one of our days at those seasons, 
lasts about twelve hours; but the sun attains at 
noon, in spring or autumn, a height of only a few 
degrees above the horizon. Then presently comes 
on the terrible winter, lasting about three of our 
months, but far more striking in its characteristics 
even than the long winter night of our polar regions. 
For, near our poles, the sun approaches the horizon 
at the hour corresponding to noon; and though he 
does not show his face, he yet lights up the southern 
skies with a cheering twilight glow. But during the 
greater part of the long night of Venus's polar regions 
the sun does not approach within many degrees of 
the horizon. Nay, he is further below the horizon 
than the midnight sun of our arctic regions. Thus, 
unless the skies are lighted up with auroral splen- 
dors, an intense darkness prevails during the polar 
winter, which must add largely to the horrors of that 
terrible season. Certainly, none of the human races 
upon our earth could bear the alternations between 
these more than polar terrors and an intensity of 
summer heat far exceeding any with which we are 
familiar on earth. 

Let us see whether the equatorial regions are 
more pleasing abodes. 

In these parts of Venus there are two summers, 
corresponding to the spring and autumn of the polar 
regions. At these seasons the sun rises day after 
day to the point overhead, and the weather corre- 
sponds for a while to that which prevails in the trop- 
ical regions of our own earth. But between these 



THE INFERIOR PLANETS 



93 



seasons the sun passes away alternately to the north- 
ern and southern skies. During the season corre- 
sponding to summer, he is above the horizon nearly 
throughout the twenty-three and a third hours of 
Venus's day; 1 but he attains no great elevation, trav- 
elling always in a small circle close around the north- 
ern pole. During the season corresponding to winter, 
he is above the horizon only a very short time each 
day, 9 and is always close to the south, attaining only 
an elevation of a few degrees at noon. Thus we have 
the following curious succession of seasons: At the 
vernal equinox a summer much warmer than our 
tropical summers; about fifty-six days later, or at the 



1 On the equator itself, as on our own, the day is always equal in 
length to the night. The above account corresponds to a place near 
the borders of the equatorial zone. 

8 In Admiral Smyth's "Celestial Cycle," the only work in which, 
so far as I am aware, the effects of the inclination ascribed to Yenus's 
axis have been at all considered, it is stated that in the year of Yenus 
there are but nine and a quarter of her days, "reckoned by the sun's 
rising and setting, owing to which the sun must appear to pass through 
a whole sign in little more than three-quarters of her natural day." He 
does not give any reasons for this remarkable statement, which most 
certainly is not correct. In all places outside the arctic circles of 
Yenus, the year contains as many natural days as there have been 
rotations of Yenus, wanting one only (as in the case of our own 
earth); in the remaining regions there will be more or fewer days, ac- 
cording as the station considered is nearer to or further from the arctic 
circle. Smyth's remark that the varying amplitude of the sun (his dis- 
tance, that is, from the east and west points), at rising or setting, would 
give travellers on Yenus readier means than our seamen have, of 
determining the longitude, is just. But the problems involved must 
be very difficult, and I wish her mathematicians joy of them. The 
cadets in our schools and training-ships have an easy time of it, com- 
pared with the unfortunate beings who are to officer the ships of 
Yenus — always supposing her axis is inclined as we have been as- 
suming. 



-zff^ 



94 OTHER WORLDS THAN OURS 

summer solstice, weather resembling somewhat the 
spring of our temperate zones, only that the night 
is exceedingly short; yet fifty-six days later there is 
another summer, as terrible as the former; and lastly, 
at the winter solstice, the days are shorter and the 
cold probably more intense than in the winter of 
places near our arctic circles. In such regions the 
contrasts, rather than either of the extremes of cli- 
mate, would be most trying to terrestrial races; and 
it is scarcely too much to say that no races subsist- 
ing upon our earth could possibly endure such re- 
markable changes, succeeding each other so rapidly. 

Lastly, the beings who inhabit the wide zones 
which are at once tropical and arctic have climates 
ranging between the two limits just considered. If 
they are near the equatorial regions, they suffer from 
all the vicissitudes of the equatorial climate, with this 
further tribulation, that, in midwinter, they do not 
see the sun even at midday, a circumstance by no 
means compensated (according to our ideas) by the 
fact that near the summer solstice the sun does not 
set. If they are near the polar regions, they have a 
summer even more terrible than the polar summer, 
and a winter scarcely less dreary and bitter. 

Fortunately for our belief in the habitability of 
Venus, astronomers are far from accepting with con- 
fidence the assertions of those observers who have 
assigned to Venus an inclination so remarkable. If 
her inclination should at all resemble the earthy 
there is every reason to believe that her physical 
habitudes also resemble those of the earth. In this 



THE INFERIOR PLANETS 95 

case, the argument from analogy, presented in the 
opening chapter of this work, seems to force upon 
us the conclusion that she is inhabited; while we 
may believe, though perhaps with less confidence, 
that a close resemblance subsists between the creat- 
ures which people her surface and those with which 
we are acquainted. 

We have no direct evidence, indeed, on which to 
ground our belief that the greater proximity of Venus 
to the sun may not be accompanied by any very re- 
markable peculiarities in the characteristics of her 
climate. But we have an indirect argument of some 
strength. If Yenus is much nearer than the earth 
to the sun, the earth, in turn, is much nearer to the 
sun than Mars is. Yet, as we shall see in the next 
chapter, we have clear evidence from telescopic ob- 
servation, and still clearer evidence as the results of 
spectroscopic research, that the climatic arrangements 
on Mars do not differ in any remarkable degree from 
those of our own earth. It would follow, therefore, 
as at least probable, that a similar resemblance pre- 
vails between the climate of the earth and that of 
Venus. So that, despite the claim which Dr. Whewell 
has put in for microscopic animalcules with siliceous 
coverings as the sole inhabitants of Venus, I can 
find no reason (if the abnormal axial inclination above 
considered is once disproved) for denying that she 
may be the abode of creatures as far advanced in 
the scale of creation as any which exist upon the 
earth. 

Gravity at the surface of Venus is so nearly equal 






96 OTHER WORLDS THAN OURS 

to terrestrial gravity, that the difference is altogether 
insufficient to introduce any noteworthy effects. The 
delicate adjustment of the sap-passages of plants to 
the force of terrestrial gravity, which Dr. Whewell 
notices in his "Bridge water Treatise/ ' might indeed 
be disturbed, if the earth's gravity were suddenly 
made equal to that of Venus. But it would be 
strangely to limit our conception of Nature's powers 
of adaptation, to suppose that therefore there can be 
no vegetation on Yenus resembling that with which 
we are familiar. 

Venus is the only planet the extent of whose at- 
mosphere has been carefully estimated. If Venus 
had no atmosphere, she would present, when horned, 
a semi -circular convexity; whereas the refractive ef- 
fects of an atmosphere, by causing the sun to illu- 
mine rather more than a full hemisphere, would tend 
to lengthen her horns. It has been found that her 
convexity when she is horned exceeds a semicircle, 
and, from the observed extent of this excess, it has 
been calculated that her atmosphere is so far more 
extensive than ours as to make its refractive effects 
on a body near the horizon about one-third greater. 
So that, as this is about the proportion in which the 
diameter of the sun as seen from Venus exceeds that 
which he presents to us, the inhabitant of Venus, like 
the inhabitant of our earth, sees the sun fully raised 
above the horizon at the moment when, but for re- 
fraction, his orb would be just concealed beneath it. 

Of the constitution of the atmosphere of Venus 
we know little. The spectrum of her light shows 



THE INFERIOR PLANETS 



97 



the dark lines which belong to the solar spectrum, 
and the Padre Secchi has noticed certain faint lines, 
which seem to indicate the presence of aqueous vapor 
in the atmosphere of the planet. But he scarcely 
gives satisfactory evidence that the lines he has thus 
seen were not due to the absorption exercised by 
aqueous vapor in our own atmosphere. The same 
observer finds, in the strengthening of the nitrogen 
lines near the F line of the spectmm, evidence that 
the atmosphere of Venus is constituted very simi- 
larly to the air we breathe. 

On the whole, the evidence we have points very 
strongly to Venus as the abode of living creatures 
not unlike the inhabitants of earth. With the sole 
exception of the inclination, which has been, with- 
out sufficient evidence, assigned to the planet's equa- 
tor, I can see nothing which can reasonably be held 
to point to an opposite conclusion. Certainly the 
strong light which the sun pours upon Venus need 
least of all be objected to, since, if there is one 
adaptative power which Nature exhibits more clearly 
than another, it is that by which the various creat- 
ures we are acquainted with are enabled to live in 
comfort under all degrees of light, from the obscur- 
ity in which the mole pursues his subterranean re- 
searches, to the blazing light of the noonday sun 
toward which (in fable, if not in fact) the eagle 
turns his unshrinking eyes. 

There is one peculiarity which yet remains to be 
noticed. Many are disposed to find, in the beauty 
of the celestial objects which deck the skies of differ- 

SOIEKOB— 1— 5 



■**& 



98 OTHER WORLDS THAN OURS 

ent planets, a certain proof that reasoning beings 
must exist who can appreciate the display. Surely 
the argument has very little force, since we know 
that myriads on myriads of ages must have passed, 
during which the glories of our own heavens were 
displayed, night after night, with none to regard 
them. The moon has passed through all her phases, 
the star of morning and of eve has shed its soft 
radiance upon the terrestrial landscape, Jupiter and 
Saturn have pursued their stately courses among the 
fixed stars, and the glories of those constellations 
which shine with equal splendor upon all the planets 
of the solar scheme have been displayed in all their 
unchanging magnificence, while as yet our earth was 
the abode but of hideous reptiles, or of yet more 
monstrous creatures in forest and in plain. 

If this argument were really of force, doubtless 
there are no planets in the whole range of the solar 
system to which it might not be applied. Each has 
some special object of beauty in its heavens, which 
is not exhibited to the rest. Certainly Mercury and 
Venus are no exceptions to this rule. The inhabitant 
of Mercury sees in Yenus an orb which, when favor- 
ably situated, far outshines in splendor the brightest 
of the planetary orbs seen in our skies. So far, in- 
deed, as light-giving power is concerned, Yenus must 
be no contemptible moon to the Mercurials when she 
is nearly in opposition. Our earth, too, with its 
companion moon, must form a noble object in the 
sky of Mercury, though, without telescopic aid, the 
moon perhaps may not be separately visible. To 



THE INFERIOR PLANETS 



W 



the inhabitants of Venus, Mercury and the earth 
must be splendid objects. The former would not 
only appear much larger than to ourselves, but, be- 
ing seen almost as favorably as we see Venus, would 
form a much more striking object in the morning or 
evening sky of that planet. The earth, as seen by 
the inhabitants of Venus, must shine much more 
splendidly than Jupiter does in our skies. Our 
moon must be distinctly visible, so that, without the 
aid of any telescope, the inhabitant of Venus has 
such evidence of the Copernican theory as would 
suffice, if properly handled, to rout the ranks of the 
Ptolemaists, supposing there have ever been people 
in Venus foolish enough to imagine the tiny globe 
they live upon to be the centre of the universe. 



CHAPTER IV 

MARS, THE MINIATURE OP OUR EARTH 

IT is singular that, among all the orbs which circle 
around the sun, one only, and that almost the 
least of the primary planets, should exhibit 
clearly and unmistakably the signs which mark a 
planet as the abode of life. We have examined 
Mercury and Venus, the only other orbs which be- 
long, like the earth and Mars, to the scheme of the 
minor planets, and we have found little to guide us 
to any certain conclusion respecting their physical 
habitudes. When we pass beyond the wide gap 
which separates the minor planets from the giant 
members of the solar family, we shall find much to 
attract our admiration, much to force upon us the 
belief that these orbs have been created to be the 
abodes of even nobler races than those which subsist 
upon our earth; but we shall find little to justify us 
in asserting that they resemble the earth in those 
habitudes which seem essential to the wants of ter- 
restrial races. The planet Mars, on the other hand, 
exhibits in the clearest manner the traces of adapta- 
tion to the wants of living beings such as we are 
(100) 



MARS, THE MINIATURE OF OUR EARTH 101 



acquainted with. Processes are at work out yonder 
in space which appear utterly useless, a real waste 
of Nature's energies, unless, like their correlatives on 
earth, they subserve the wants of organized beings. 

I would not indeed insist, as some have done, too 
strongly upon this argument. I know that on every 
side we see tokens of an exuberant activity in Nat- 
ure, which, according to our ideas, may appear to 
savor of wastefulness. The cloud which has been 
raised by the solar energies from tropical seas, and 
which the winds have wafted over continents, may 
shed its waters on the sea or in the desert, where 
seemingly they are wholly wasted. Winds may 
spend their force apparently in vain. And in a 
thousand ways Nature's busy forces may be at work 
where we, in our short-sightedness, can see no use- 
ful purpose which they subserve. 

But there is a marked distinction between such 
apparent instances of wasteful action, and the sys- 
tematic processes which are taking place over the 
globe of Mars. 

Little as we can appreciate the real character of 
Nature's work upon our earth, we can yet dimly 
trace out a necessity (depending upon the order 
which actually exists) for that which yet appears to 
resemble waste. We see, for instance, that if a 
country or a continent is to be provided with a due 
supply of rain, without supernatural intervention at 
every step of the process, that result can only be 
secured by what may be described as a random dis- 
tribution, involving always what to lis resembles 



102 OTHER WORLDS THAN OURS 

waste. If, out of a thousand showers, ten only fall 
go as to be useful to the land, the object of Nature 
is subserved, and the useful rainfalls serve to ex- 
plain the seemingly wasted ones. In reality, of 
course, there has not been a random distribution, 
nor has there been any waste; I infer, merely, that 
a sort of purpose is, in such a case, dimly seen, even 
by man, who can see so short a distance into the 
workings of the Almighty. 

But in the case of Mars we have no such ex- 
planation of the processes we observe, if we dismiss 
our belief that he is the abode of living creatures. 
For if Mars be, indeed, untenanted by any forms of 
life, then these processes going on year after year, 
and century after century, represent an exertion of 
Nature's energies which appears absolutely without 
conceivable utility. If one cloud, out of a hundred 
of those which shed their waters upon Mars, supplies 
in any degree the wants of living creatures, then the 
purport of those clouds is not unintelligible; but if 
not a single race of beings peoples that distant 
world, then indeed we seem compelled to say that, 
in Mars at least, Nature's forces are wholly wasted. 
Such a conclusion, however, the true philosopher 
would not care needlessly to adopt. 

Let us consider what astronomy has taught us 
respecting the ruddy planet. 

The globe of Mars is about five thousand miles 
in diameter, so that his linear dimensions bear to 
those of the earth the proportion of about five to 
eight. His surface, therefore, is less than that of the 



MARS, THE MINIATURE OF OUR EARTH 103 



earth in the proportion of about twenty-five to sixty- 
four, or, more exactly (and more conveniently), the 
surface of the earth is two and a half times as 
extensive as that of Mars. 

The substance of Mars has an average density 
rather less than three-fourths of our earth's, or very 
nearly four times that of water. Thus gravity at his 
surface is much less than terrestrial gravity. It is, 
in fact, even less than gravity at the surface of Mer- 
cury, insomuch that one of our pound weights placed 
at • the surface of Mars would weigh but 6 ozs. 3 
dwts., instead of nearly seven ounces as on Mercury. 
I have already dwelt on the effects of such a relation 
as this, and shall have occasion, when describing the 
habitudes of Jupiter, to discuss the converse rela- 
tion. But I may remark, in passing, how singular 
it is that we should be compelled to people the 
smallest planets with the largest inhabitants, if we 
wish to bring the inhabitants of different orbs to 
Lbout the same scale of activity. A Daniel Lambert 
on Mars would be able to leap easily to a height of 
&ve or six feet, and he could run faster than the 
best of our terrestrial athletes. A man of his weight, 
but proportioned more suitably for athletic exercises, 
could leap over a twelve-foot wall. On the other 
hand, a light and active stripling removed to Ju- 
piter would be scarcely able to move from place to 
place. On the sun his own weight would simply 
crush him to death. 

Mars travels in an orbit of considerable eccen- 
tricity; in fact, the centre of his orbit is no less 



104 OTHER WORLDS THAN OURS 

than thirteen millions of miles from the sun. Ac- 
cordingly, the light and heat he receives from that 
luminary vary to an important extent. In fact, he 
gets about half as much heat and light again when 
in perihelion as when in aphelion. This circum- 
stance affects to an important extent the climatic 
relations of his two hemispheres, as we shall pres- 
ently see. 

When Mars is at his mean distance from the sun, 
the light and heat he receives are less than ours in 
the proportion of about four to nine. The length 
of his year also constitutes a noteworthy circum- 
stance in which his habitudes differ from those of 
our earth. His year contains very nearly six hun- 
dred and eighty -seven of our days, so that each of 
the Martial quarters lasts about five and two-thirds 
of our months. But, owing to the eccentricity of 
his orbit, the winter and summer of the northern 
and southern hemispheres are not equal. The Mar- 
tial day is nearly forty minutes longer than ours. 1 

His equator is inclined at an angle of about 
twenty-seven and a quarter degrees to the plane of 
his orbit, and as the corresponding inclination in the 
case of the earth is about twenty-three and a half 
degrees, it will be seen that his seasonal changes 
do not differ much in character, so far at least as 
they depend on inclination, from our own. 

1 More exactly, the length of the Martial day is 24h. 3*7m. 22.735s. 
This estimate I have obtained by comparing pictures taken by Hooke in 
1666, and by Dawes and Browning in 1866-1869 — with precautions suffic- 
ing to secure that no complete rotation should anywhere be lost sight ol 



MARS, THE MINIATURE OF OUR EARTH 105 



The axis of Mars is so situated that the summer 
of his northern hemisphere occurs when he is at his 
greatest distance from the sun. The same relation 
holds in the case of the earth, the sun being one 
million five hundred thousand miles nearer to us in 
winter than in summer, whereas, to those who live 
in the southern hemisphere, he approaches nearer in 
summer than in winter. But the effects resulting 
from the relation in the case of Mars must be very- 
much more striking than those we recognize. For, 
whereas the sun gives only one-fifteenth more heat 
to the whole earth in January than he does in July, 
the sun of Mars gives half as much light again in 
perihelion as in aphelion. The summer of the north- 
ern hemisphere of Mars must be rendered much 
cooler and the winter much warmer by this arrange- 
ment. On the other hand, the contrast between the 
summer and winter of the southern hemisphere is 
rendered more striking than it otherwise would be. 

It is, however, the telescopic aspect of Mars, 
rather than relations such as we have been dealing 
with, that affords the most interesting evidence re- 
specting the fitness of the planet to be the abode of 
living creatures. Although the least but one among 
the primary planets — a mere speck compared with 
Jupiter and Saturn — Mars has been examined more 
minutely and under more favorable circumstances 
than any object in the heavens except the moon. 
He does not approach us so closely as Yenus, nor 
does his disk appear so large as Jupiter's, yet he is 
seen more favorably than the former planet, and on 



106 OTHER WORLDS THAN OURS 

a larger scale, in reality, than the latter. In fact, 
whereas Venus is one of the most unsatisfactory of 
all telescopic objects, Mars is one of the most pleas- 
ing; and, whereas Jupiter is always more than three 
hundred and eighty millions of miles from us, Mars 
sometimes approaches us within less than forty mil- 
lions of miles. 

Yet even this distance is enormous, and it affords 
high evidence of the skill with which modern tele- 
scopes are constructed and used, that astronomers 
should have been able to span that mighty gulf, 
and to bring from beyond it reliable information re- 
specting the structure of so distant a world. 

Such information has been brought, however, and 
is full of interest. 

Viewed with the naked eye, the most remarkable 
feature Mars presents is his ruddy color. In the 
telescope this color is not lost, but, instead of char- 
acterizing the whole surface of the planet, it is con- 
fined to particular regions — the intermediate parts 
being for the most part darker, and of a somewhat 
greenish hue. But a noteworthy feature adds largely 
to the beauty of the picture presented by the globe 
of Mars. Two bright spots of white light are seen 
on opposite sides of his disk, presenting precisely 
such an appearance as we might imagine the snowy 
poles of our earth to exhibit to an astronomer on 
the planet Venus. 

Toward the edge of the disk, the ruddy and the 
greenish tracts are lost in a misty whiteness, which 
grows gradually brighter up to the very border of 



MARS, THE MINIATURE OF OUR EARTH 107 



the planet. We shall presently see that this pecu- 
liarity, rightly understood, is one of the most instruc- 
tive features of the planet's aspect. 

No telescopist has yet been able to recognize a 
satellite attending on the Planet of War. 

It was discerned, more than two hundred years 
ago, that the reddish spots on Mars, and the darker 
regions which lie between them, are not accidental 
or variable phenomena, but represent permanent pecu- 
liarities of the Martial surface. Cassini, with one of 
those outrageously long telescopes which were used 
before the invention of achromatic refractors, was 
the first to discover this. But the ingenious Hooke 
seems to have obtained better views of Mars in 
1666. At least, his pictures of the planet are the 
only ones taken in the seventeenth century, in which 
I can recognize the now well-known aspect of the 
Martial continents and oceans. 

Since then, Maraldi and the Herschels, Arago, 
Secchi, Kunowski, Beer and Madler, and a host of 
other eminent astronomers, have not thought the 
study of the planet's aspect beneath their notice. 
Within the last few years, also, this work has been 
prosecuted by Nasmyth and Jacob, Delarue and 
Phillips, and finally and most successfully by Lock- 
yer and Dawes. The last-named observer, espe- 
cially, whose acuteness of vision earned for him the 
title of the eagle-eyed, took so many and such ad- 
mirable views of the planet as to render it possible 
to form a globe of Mars. Sir William Herschel had 
charted the planet, and Messrs. Beer and Madler had 



108 OTHER WORLDS THAN OURS 

made improved Martial maps; while Professor Phil- 
lips, from observations made by himself and Mr. 
Lockyer, had constructed two globes of Mars in 
which many features were presented. But Mr. 
Dawes's pictures of the planet were sufficient, when 
carefully compared, for the formation of a globe in 
which no large area of the planet should be left 
bare of details. He intrusted to me no less than 
twenty-seven drawings of Mars, the choicest speci- 
mens of a very large series, that I might chart the 
planet from them. The accompanying chart of Mars, 
in which the darker (black) parts of the planet are 
assumed to be seas, and the reddish (white) tracts 
continents, exhibits the results obtained from the 
study of the complete series. This chart is on the 
stereographic projection, and is inverted — the south 
polar regions, that is, are at the top — because the 
telescopes commonly used by observers exhibit in- 
verted views of the celestial objects. 1 At the top 
of the map we see the icy region which lies at the 
southern pole of Mars. Around that region is a sea 
unnamed in the map. Then along the southern tem- 
perate zone there lie several tracts of Martial land, 
named after Cassini, Lockyer, and other astronomers. 
These regions appear to form a continuous land-belt 
round the temperate zone; though there is some un- 
certainty on this point, owing to the fact that the 
coast-line is not often very distinctly visible. We 

1 Mr. Browning, P.R.A.S., has formed a globe of Mare from my 
chart, and publishes an interesting series of photographs of this globe 
which give fine stereoscopic effects. 



MARS, THE MINIATURE OF OUR EARTH 



109 




1 



, 



110 OTHER WORLDS THAN OURS 

now approach, however, a part of the map where all 
the features are thoroughly recognized and perma- 
nent. Next to the circle of land just described, 
there is a nearly complete circle of water, one strip 
only of land connecting the equatorial continents of 
Mars with the south-temperate zone of minor con- 
tinents. Beginning at the eastern or left-hand ex- 
tremity of the map, we have a long sea, called 
Maraldi Sea, parallel to which runs Hooke Sea, 
trending in a northwesterly direction, and so run- 
ning into Dawes Ocean; still further west are two 
vast islands, called Jacob Island and Phillips Isl- 
and, between which runs Arago Strait. Beyond 
these islands lies Delarue Ocean, communicating by 
narrow straits with two strikingly similar seas. Here 
the zone of water ends, and we have only to note 
further, respecting it, that in Delarue Ocean there 
is a large island, which presents so strikingly bril- 
liant an aspect that it has been supposed to be cov- 
ered (ordinarily) with snow. It has been called 
Dawes's Ice Island. 

I now come to the most remarkable feature of 
the Martial geography — or perhaps I ought rather to 
say, areography. This is the great equatorial zone 
of continents. There are four of these. On the left 
of the map is Herschel I. Continent. Next is Dawes 
Continent, the largest of the four, and separated from 
the former by a long sea called Kaiser Sea. This sea 
is one of the most striking marks on the planet, and 
has been recognized from the earliest days of tele- 
scopic observation. It is connected toward the east 



MARS, THE MINIATURE OF OUR EARTH 111 

with a flask-shaped sea, somewhat resembling the 
two which lie at the western extremity of the zone 
of water just described. At its northernmost end it 
turns sharply westward, and forms the southern boun- 
dary of Dawes Continent. Further west lies Madler 
Continent, separated from Dawes Continent by a long 
strait, which runs almost directly north and south. 
Lastly, there is Secchi Continent, separated from 
Madler Continent by Bessel Inlet and from Herschel 
Continent by Huggins Inlet. A large lake on the 
last-named continent is worthy of notice on account 
of its singular shape. It consists of two bell-shaped 
seas connected by a narrow and sharply -curved strait. 

The northern half of Mars has not been so thor- 
oughly examined as the southern, for a reason which 
will presently be mentioned. It is known, however, 
that, in all essential respects, it resembles the south- 
ern hemisphere. Next to the equatorial zone of con- 
tinents there comes a zone of water, expanding at one 
point into Beer Sea, and at another into Tycho Sea. 
Then comes a zone of land, called Laplace Land, in 
which lies an enormous lake called Delambre Sea. 
Next is a narrow zone of water called the Schroter 
Sea, and so we reach the north-polar ice-cap. 

I have been speaking of the spots on Mars as 
though they undoubtedly represented land and water. 
But many may be disposed to question the evidence 
we have on this point — to ask why the ruddy spots 
should be held to be continents or islands, and the 
greenish-colored markings to be oceans, seas, and 
lakes. We know that, for a long time after the in- 



": 



jl12 other worlds than ours 

vention of the telescope, astronomers called the darker 
portions of the moon seas. They spoke of the Sea 
of Serenity, the Sea of Crises, the Sea of Humors, 
and so on, and we now know for certain that these 
dusky regions are not seas. It may be asked, there- 
fore, how we can feel certain that the dark spots on 
Mars are oceans. 

At first sight, this question seems a difficult one 
to answer. The most powerful telescopes have been 
directed toward the moon, without affording any sat- 
isfactory information respecting the condition of its 
surface. Mars, therefore, which lies — even under the 
most favorable circumstances — more than one hun- 
dred and sixty times further from us than the moon, 
might be thought to be altogether beyond the reach 
of our telescopists — so far, at least, as any knowledge 
of the Martial surface is concerned. But one impor- 
tant distinction between Mars and the moon must be 
carefully attended to. The surface of the moon is 
always the same — no natural processes seem ever to 
take place over that scene of desolation, though the 
moon is exposed to contrasts of temperature, com- 
pared with which the distinction between the in- 
tensest heat of our summers and the bitterest cold 
of our winters seems altogether evanescent. But, on 
Mars, the case is certainly different. Whatever opin- 
ion we may form respecting Martial habitudes, whether 
we assume or not that Mars is the abode of any forms 
of animal life, there can be no question whatever that 
physical processes of change are taking place on a 
grand scale in that distant world. Many evidences of 



MARS, THE MINIATURE OF OUR EARTH 113 

this can be at once adduced. We have spoken of 
the Martial features as constant. They differ, for in- 
stance, from the markings on Jupiter, which are as 
changeful as the aspect of our April skies. But 
though the same marking may have been seen by 
Hooke in 1666, by Maraldi in 1720, by Herschel in 
1780, by Beer and Madler in 1830-37, and by Dawes 
in 1852-65, yet it by no means follows that it is al- 
ways visible when the part of Mars to which it be- 
longs is turned toward us. A veil is sometimes drawn 
over it for hours or even days together. And this 
veil has nothing to do with the distinctness or indis- 
tinctness with which our own atmosphere permits us 
to see the planet. A spot will be blurred and indis- 
tinct when a neighboring marking is exhibited with 
unusual clearness. 

Let us consider an instance of this peculiarity. 
On October 3, 1862, Mr. Lockyer was observing 
Mars late in the evening. He noticed that a part 
of Dawes Ocean, where it borders on Herschel Con- 
tinent, was hidden from view. In place of the or- 
dinarily dark aspect of this region, a faint, misty 
light, with ill-defined borders, was observable. As 
the evening progressed, he noticed that the outlines 
gradually became clearer, but, when he gave up ob- 
servation (at about half -past eleven), the white light 
still continued to veil the outline of a part of Dawes 
Ocean. Now, Mr. Dawes observed Mars on the same 
night, at a quarter-past twelve. The drawing which 
he took at that hour shows that the process of clear- 
ing up, noticed by Mr. Loo£yer as being in progress 



114 OTHER WORLDS THAN OURS 

in the earlier part of the night, had, by the time 
Mr. Dawes began work, entirely lifted off the veil 
which concealed the coast-line. The remains of the 
misty light seen by Lockyer are still to be detected 
in Mr. Dawes's drawing, but they have passed 
further south, and no longer hide the shores of 
Dawes Ocean. 

The Padre Secchi, of the Collegio Eomano, states 
that he has often noticed similar appearances, while 
observing Mars with the fine refractor in the observa- 
tory of that institution. 

But yet another peculiarity of the same sort re- 
mains to be mentioned. Mars, as 1 have said, has 
his winter and summer seasons. Since we know the 
position of the Martial equator upon his surface, we 
can tell what season is in progress in either hemi- 
sphere at any given time. Now, it has been noticed 
that, when it is winter in one hemisphere, and there- 
fore summer in the other, the former hemisphere is 
nearly always hidden from view by just such a veil 
as I have spoken of above. 

I may remark, in passing, that this peculiarity has 
led many observers to form very erroneous impres- 
sions respecting the distribution of land and water 
over the surface of Mars. Seeing one hemisphere 
covered for weeks together with whitish light, they 
have concluded that there are no oceans there; and 
if they have no other opportunity of observing the 
planet, the mistaken impression remains, and is 
published to the world with all the authority of the 
observer's name. 



MARS, THE MINIATURE OF OUR EARTH 115 

Now, what is this veil which, sometimes for a 
few hours or days, at others for months together, is 
drawn over the features of the Martial globe? Have 
we any terrestrial analogies, by means of which we 
may interpret this phenomenon? 

To answer these questions, let us conceive the 
case of an observer on Yenus watching our earth. 
Would such an observer always see the features of 
this globe with equal distinctness? When heavy 
masses of cloud are drawn over a wide expanse of 
country — spreading often, as meteorologists record, 
for hundreds and even thousands of miles — can we 
suppose that the astronomer on Yenus could pierce 
through the veil? Since we cannot see the bright 
body of the sun through a dense cloud- veil, we may 
be certain that the observer on Yenus cannot see the 
oceans and continents of our earth when thus cloud- 
shadowed. So far as the cloud-veil extends, the 
lands and seas of this globe would be to him, at 
such a time, as though they were not. 

Here, then, we have an argument from analogy 
for supposing that the veil, which from time to time 
conceals the Martial features, may resemble terres- 
trial cloud-banks. Let us next inquire whether there 
is anything in the behavior of the Martial veil to 
justify this view. 

It is clear that, if we held the concealing medium 
to be of a cloudy nature, the disappearance of the 
features of the hemisphere which is passing through 
the Martial winter would indicate that in winter the 
Martial skies are more clouded than in summer. 



116 OTHER WORLDS THAN 0VR8 

We know that this is the case on our own earth — 
that fogs and mists, clouds, rain, and snow, are 
phenomena far more frequently observed in winter 
than in summer. We know also why it is so. The 
cold winter air is unable to retain the aqueous vapor 
continually passing into it, and is thus forced to pre- 
cipitate this vapor in one or other of the forms just 
named. Nor can we see any reason why the Martial 
atmosphere, supposing it to resemble our own, 
should not act in precisely the same manner. Thus 
we recognize, in the remarkable seasonal peculiarity 
above described, what seems to be the exact counter- 
part of processes recognized upon the earth. 

And though I admit that there is considerable 
objection to the mode of argument I am next going 
to make use of, yet, as it is one which has great 
weight with many minds, and is not without its own 
peculiar force, I feel justified in applying it as a 
subsidiary support to the views I am discussing. It 
is known that the peculiarities which characterize 
terrestrial atmospheric phenomena tend in an impor- 
tant manner to mitigate the extremes of summer and 
winter temperature. The clouds which hang o\?er 
our winter skies, far from acting to increase the 
coldness of winter through their effect in keeping 
off the sun's rays, in reality represent an enormous 
supply of heat brought from warmer parts of the 
earth, and liberated for our benefit as the invisible 
vapor of water assumes the form of cloud or rain. 
And although these processes are strictly in accord- 
ance with natural laws, yet we are justified in recog- 



MARS, THE MINIATURE OF OUR EARTH 117 



nizing them as evidences of the beneficence of the 
Almighty. Now, on Mars, we may be sure, the win- 
ters tend to be far more bitter than ours, partly 
because of his greater distance from the sun, but 
chiefly because of the more marked contrast exist- 
ing between his various seasons. Hence, if there are 
living creatures on Mars, it can scarcely be doubted 
that an arrangement such as that which prevails on 
earth is yet more necessary to the welfare of the 
Martialists. Thus, we derive an argument from the 
a priori consideration of the nature of Martial re- 
quirements, to favor our interpretation of the phe- 
nomena actually observed. 

Perhaps the reader may be disposed to inquire 
whether the clearing up of a portion of the Martial 
disk observed by Lockyer and Dawes admits of in- 
terpretation in a similar way. To this it may be 
replied that, from the observed position of the region 
in question, the Martial time of day there must have 
been somewhere about noon when Mr. Lockyer be- 
gan his observations, and about one o'clock in the 
afternoon (according to our terrestrial mode of reck- 
oning) when Mr. Dawes observed the planet. It is 
no uncommon thing to see our terrestrial skies clear 
up soon after midday; and if the veil which conceals 
the Martial features is really cloudy, this is precisely 
what happened out yonder, forty millions of miles 
away from us, on the day in question. 

I think the reader will at least concede that the 
explanation here given of these peculiarities is more 
natural than one which was put forward some time 






118 OTHER WORLDS THAN OURS 

since by an eminent French astronomer. He urged 
that Martial vegetation, instead of being green like 
ours, is red; hence in the Martial summer the sur- 
face, as seen by us, assumes a ruddy aspect, while 
the wintry hemisphere loses its ruddy tint. Accord- 
ing to this interpretation, such changes as were no- 
ticed by Secchi would indicate the sudden blooming 
forth of Martial vegetation over hundreds of square 
miles of the Martial surface. 

To the evidence already dealt with may be added 
that which is afforded by the whiteness of the disk 
of Mars near the edge. Knowing that the parts of 
Mars which thus appear concealed in mist are those 
where it is morning or evening to the Martialists, we 
see a close analogy here to terrestrial relations, since 
our own skies are commonly more moisture-laden in 
the morning and evening than near midday.' 

I may here pause, in passing, to notice tinder 
what difficulties the observation of Mars is conducted 
by the terrestrial observer. To begin with, the sky 
must be exceptionally clear; and none but the prac- 
ticed observer knows how seldom there occurs what 
is called "a good observing night." Then it must 
be a fine day for the Martialists, for clouds over 



1 In the "Popular Science Review" for January, 1869, 1 have indicated 
a subsidiary explanation of this peculiarity, founded on the probable shape 
of the Martial clouds. For the same reason that, near the horizon, our 
own cumulus clouds seem more closely packed than overhead, the Mar* 
tialists would see a clearer sky overhead than near the hormon. It follows, 
at once, that we should see those parts of the surface of Mars best which 
we look upon in a nearly vertical direction, that is, the central parts of 
his disk. 



MARS, THE MINIATURE OF OUR EARTH 119 

Mars, or even an imperfectly clear atmosphere, must 
produce quite as bad an effect in spoiling the defi- 
nition of Martial features as similar phenomena on 
earth. Again, Mars only comes into a favorable 
position once in every two and a quarter years, con- 
tinuing to be well placed for only a few months. 
Thus it happens that, although Mars has been tele- 
scopically observed for more than two hundred 
years, the actual time during which he has been 
favorably placed for observation has been very 
much less; and, taking into account all the require- 
ments for good definition, it may be said that Mars 
has not been under really effective observation for 
more than a very few days. 

Of course, if we admit that the vaporous envelope 
which occasionally hides parts of Mars is aqueous, 
we must believe in the existence of oceans upon 
Mars. And, from our knowledge of the appearance 
of our own seas, we should immediately recognize 
the greenish parts of Mars as the Martial oceans, and 
look upon the ruddy parts as continents. We have 
seen that the behavior of the vaporous envelopes 
corresponds to that of our own clouds and fogs. 
But it might be thought possible that the vapors 
arise from fluids other than water; that, in fact, a 
state of things exists upon Mars wholly different 
from that which prevails upon our own earth. 

Ten. years ago it would have been very difficult 
to disprove such an argument as this, however 
bizarre it may seem. But the wonderful powers of 
the spectroscope have been applied to this question, 






120 OTHER WORLDS THAN OURS 

and there is no mistaking the results which have 
been obtained. We must premise that this is hardly 
a favorable case for the application of spectroscopic 
analysis, which (as available to the astronomer) deals 
most effectively with self-luminous objects. Still, 
there was a possibility that the light which comes 
from Mars might have been so acted upon by vapors 
in the Martial atmosphere, that its spectrum would 
be affected in an appreciable manner. 

Mr. Huggins examined Mars in 1864 without sat- 
isfactory results, but at the opposition of Mars in 
1867 he was more successful. In the following de- 
scription of his most striking observation I epitomize 
his account: On February 14th he examined Mars 
with a spectroscope attached to his powerful eight- 
inch refractor. The rainbow - colored streak was 
crossed, near the orange part, by groups of dark 
lines agreeing in position "with lines which make 
their appearance in the solar spectrum when the sun 
is low down, so that its light has to traverse the 
denser strata of our atmosphere.' ' To determine 
whether these lines belonged to the light from Mars 
or were caused by our own atmosphere, Mr. Hug- 
gins turned his spectroscope toward the moon, which 
happened to be nearer the horizon than Mars, so 
that the atmospheric lines would be stronger in the 
moon's spectrum than in that of the planet. But 
the group of lines referred to was not visible in the 
lunar spectrum. Hence it was clear that they belong 
to the Martial atmosphere, and not to ours. 

I have said that these lines appear in the solar 



MARS, THE MINIATURE OF OUR EARTH 121 



spectrum when the sun is shining through the denser 
strata of our atmosphere. Let us consider a moment 
the light which this fact throws on the nature of the 
Martial atmosphere. It must contain at least those 
constituent vapors whose existence in our atmosphere 
causes the appearance of these lines in the solar 
spectrum. Hence there must be some similarity be- 
tween the Martial atmosphere and our own. But 
we know, from the researches of the Padre Secchi, 
that it is the aqueous vapor in our air which causes 
the appearance of the lines in question. Hence 
there must be aqueous vapor in the Martial atmos- 
phere. 

This discovery at once justifies the title of the 
present chapter. Let us consider what a number of 
interesting results follow from it. 

The water in the Martial air must be raised from 
seas and rivers upon the planet. These, therefore, 
consist of water and not of other fluids. The two 
white spots, then, on the Martial disk are no longer 
doubtful appearances. Before the discovery that 
water exists on Mars, it was perhaps somewhat bold 
to pronounce that these spots certainly indicate the 
presence of ice-fields around the Martial poles, re- 
sembling those which exist around the poles of the 
earth. Sir William Herschel, indeed, with that con- 
fidence which he always showed when he had a 
trustworthy analogy to guide him, came to this con- 
clusion on the strength of the correspondence be- 
tween the changes of the two spots and the progress 
of the Martial seasons. But many astronomers felt 

SOIEJilUB— 1-^6 



122 OTHER WORLDS THAN OURS 

that there was still room to doubt whether we could 
really speak of the spots as 

"The snowy poles of moonless Mars." 

Now, however, we know that they can be no other 
than snow-caps. Nay, if Mars were so far off that 
we could not distinguish these spots, we could yet, 
on the strength of what the spectroscope has taught 
us, pronounce confidently that his polar regions must 
be ice-bound. 

Let us proceed a step or two further. We have 
8een that there are oceans on Mars; we know that 
clouds and vapors rise from those oceans and are 
wafted over his continents; and, finally, we have 
learned that snow falls on the Martial polar regions. 
These things are very interesting in themselves, but 
they indicate the occurrence of processes yet more 
interesting. The formation and the dissipation of 
clouds are among the most important of all the proc- 
esses by which Nature arranges and modifies the 
temperature of our earth. The heat of the sun's rays 
is used up, so to speak, in raising aqueous vapor 
from the surface of the ocean. Thus the air is ren- 
dered cooler than it otherwise would be, and this 
takes place just where coolness is most needed. But 
the aqueous vapor, once raised, is swept by the 
winds to other regions. So long as the air remains 
warm, the aqueous vapor remains unchanged; but, 
so soon as it has been carried to colder regions, it is 
condensed into the form of cloud or mist, and while 
changing to this form it parts with the heat which 



MARS, THE MINIATURE OF OVR EARTH 128 

had turned it into vapor. Thus where heat is in ex- 
cess, it is used up in forming aqueous vapor, and 
where heat is wanted there the aqueous vapor dis- 
tributes it. 

We see, then, that on Mars there exists the same 
admirable contrivance for tempering climates which 
we find on our own earth. 

But let us consider yet another office fulfilled by 
aqueous vapor. It not only serves to convey the 
heat from the warmer parts of the earth to those 
regions where heat is most needed. It forms clouds 
which serve to shelter the earth from the sun's heat 
by day, and to prevent the escape of the earth's heat 
by night, which also, in refreshing rains, "drop fat- 
ness on the earth." Now, the clouds on Mars are 
certainly dissipated in some way, because, as I have 
said, astronomers have repeatedly seen them dis- 
appear. And doubtless, like our own clouds, they 
are often dissipated by the sun's heat. But we may 
take it for granted that, like our terrestrial clouds, 
they are also often dissipated by falling in rain. 
Thus the Martial lands are nourished by refreshing 
rainfalls; and who can doubt that they are thus 
nourished for the same purpose as our own fields 
and forests — namely, that vegetation of all sorts may 
grow abundantly? 

But yet, again, the transit of clouds from place to 
place implies the existence of aerial currents. Clouds 
cannot, indeed, even form and be dissipated without 
occasioning wind -currents; and it need hardly be said 
that the Martial clouds could not be carried to bib 



124 OTHER WORLDS THAN OURS 

polar regions, there to fall in snow, unless the atmos- 
pheric currents on Mars were extensive and persistent. 
We see, then, that Mars has winds as our earth has. 
Doubtless his trade -winds are less marked than ours, 
because his surface rotates less rapidly than the 
earth's, his globe being much smaller, while his ro- 
tation-period is slightly greater. But he has less 
need for trade-winds, his oceans being so much less 
extensive than ours. No Columbus on Mars has ever 
needed the persistent breath of easterly winds to en- 
courage him on his voyage to an undiscovered con- 
tinent. Eather, the intricate navigation of the narrow 
Martial seas would be favored by variable breezes. 
But the great purposes which the circulation of our 
own atmosphere subserves are carried out efficiently 
out yonder on Mars. The air is cleansed and puri- 
fied, its thermal and electrical conditions are regu- 
lated, clouds are wafted from place to place; and, in 
fine, the atmosphere is rendered fit for all those pur- 
poses for which, like our own, it has doubtless been 
created. 

We may trace yet further, however, the results 
which flow from the existence of aqueous vapor in 
the atmosphere of Mars. We see the polar snows 
aggregating in the Martial winter and diminishing in 
the Martial summer. And we know that, on our own 
earth, the increase and the diminution of the polar 
snows are processes intimately associated with the 
formation and maintenance of the oceanic circulation. 
Doubtless much yet remains to be done before that 
system of circulation will be fully understood. The 



MARS, THE MINIATURE OF OUR EARTH 125 



rival views which have been maintained by Sir John 
Herschel and Captain Maury have served to throw 
a certain air of doubt over the theory of ocean- 
currents. 1 But whether we ascribe the equatorial 
currents of our oceans to the trade-winds with Her- 
schel, or to differences of specific gravity with Maury, 
we see that, in the first place, both causes operate in 
the case of Mars, and secondly, that the submarine 
return-currents from our polar regions must, at any 
rate, be due to the presence of ice in the polar seas. 
So that undoubtedly the Martial oceans, so far as 
their peculiar conformation will permit, are traversed 
by currents in various directions and at various depths. 
Then, lastly, there must be rivers on Mars. The 
clouds which often hide from our view the larger part 
of a Martial continent, indicate a rainfall at least as 
considerable (in proportion) as that which we have on 
the earth. The water thus precipitated on the Martial 
continents can find its way no otherwise to the ocean 
than along river-courses. 






1 If Herschel has completely overthrown Maury's theory that cur- 
rents are altogether due to differences of specific gravity, saltness. and 
so on, Maury has at least been as successful in overthrowing Herschei's 
theory that the currents are due to the trade-winds, A theory more 
probable than either is, I think, that according to which the whole 
system of circulation is set in motion by the continual evaporation going 
on in equatorial seas. Thus, by a process resembling suction, an in- 
draught of cold water is caused, and this water, coming from higher 
latitudes, where the earth's eastwardly motion is less, to lower lati- 
tudes, where the eastwardly motion is greater, produces the relatively 
cold and westwardly equatorial currents which exist in the Atlantic, 
Indian, and Pacific Oceans. Recent researches into the temperature 
of the deep sea have tended strongly to confirm these views, which I 
dealt with at some length in the "Intellectual Observer" for May, 1867. 









126 OTHER WORLDS THAN OURS 

As to the nature of these rivers again, we may 
form conjectures founded on trustworthy analogies. 
The mere existence of continents and oceans on Mars 
proves the action of forces of upheaval and of depres- 
sion. There must be volcanic eruptions and earth- 
quakes, modelling and remodelling the crust of Mars. 
Thus there must be mountains and hills, valleys and 
ravines, water-sheds and water-courses. All the vari- 
ous kinds of scenery which make our earth so beauti- 
ful have their representatives in the ruddy planet. 
The river courses to the ocean, by cataract and lake, 
here urging its way impetuously over rocks and bowl- 
ders, there gliding with stately flow along its more 
level reaches. The rivulet speeds to the river, the 
brook to the rivulet, and from the mountain recesses 
burst forth the refreshing springs which are to feed 
the Martial brooklets. 

Who can doubt what the lesson is that all these 
things are meant to teach us? So far, let it be re* 
membered, we have been guided onward by no spec- 
ulative fancies, but simply by sober reasoning. But 
can we pause just here? Shall we recognize in Mars 
all that makes our own world so well fitted to our 
wants — land and water, mountain and valley, cloud 
and sunshine, rain, and ice, and snow, rivers and 
lakes, ocean-currents and wind-currents, without be- 
lieving further in the existence of those forms of life 
without which all these things would be wasted? 
Surely, if it is rashly speculative to say of this 
charming planet that it is the abode of life — if we 
must, indeed, limit ourselves to the consideration of 



MARS, THE MINIATURE OF OUR EARTH 127 



what has been absolutely seen — it is yet to speculate 
ten thousand times more rashly to assert, in the face 
of so many probable arguments to the contrary, that 
Mars is a barren waste, either wholly untenanted by 
living creatures, or inhabited by beings belonging to 
the lowest orders of animated existence. 



3*** 



CHAPTER V 

JUPITER, THE GIANT OP THE SOLAR SYSTEM 

PASSING over the zone of asteroids, we come 
now to the noblest of all the planets — the 
giant Jupiter. If bulk is to be the measure 
of a planet's fitness to be the abode of living creat- 
ures, then must Jupiter be inhabited by the most 
favored races existing throughout the whole range of 
the solar system. Exceeding our earth some twelve 
hundred and thirty times in volume, and more than 
three hundred times in mass, this magnificent orb 
was rightly selected by Brewster as the crowning 
proof of the relative insignificance of the earth in 
the scale of creation — assuming only that we can 
indeed gauge the purposes of the Creator by the 
familiar tests of measure and weight. 

Or if we estimate Jupiter rather by the forces in- 
herent in his system, if we contemplate the enormous 
rapidity with which his vast bulk whirls round upon 
its axis, or trace the stately motion with which he 
sweeps onward on his orbit, or measure the influences 
by which he sways his noble family of satellites, we 
are equally impressed with the feeling that here we 
(128) 



JUPITER, GIANT 01 SOLAR SYSTEM 



129 



have the prince of all the planets, the orb which, of 
all others in the solar scheme, suggests to us concep- 
tions of the noblest forms of life. 

The very symmetry and perfection of the system 
which circles round Jupiter have led many to believe 
that he must be inhabited by races superior in intel- 
ligence to any which people our earth. The motions 
of these bodies afford indeed to our astronomers a 
noble subject of study. Our most eminent mathema- 
ticians have given many hours of study to the phe- 
nomena which the four moons present to the terrestrial 
observer. But we can trace only the general move- 
ments of the satellites of Jupiter. Their minor dis- 
turbances, the effects of the varying influences which 
the sun and Jupiter exert upon them, and which the 
moons exert upon each other, must tax the powers 
of far abler mathematicians even than he who " sur- 
passed the whole human race in mental grasp.' * 

But, after all, we must judge of Jupiter rather ac- 
cording to the evidence we have, and the analogies 
which are most directly applicable to the case, than 
according to fancies such as these. We know that 
the sun, which surpasses Jupiter in weight and vol- 
ume even more than Jupiter surpasses the earth, is 
yet not the abode of life, so that mere size and mass 
must not be held to argue habitability. We know 
that many meteors and comets sweep through spaces 
more swiftly than the vast bulk of Jupiter, so that 
the energies indicated by mere velocity of motion, 
whether orbital or rotational, must be equally disre 
garded. Nor must we forget that, ages before men 



130 OTHER WORLDS THAN OURS 

studied the motions of our own moon, she presented 
the same noble subject of study that she forms in 
our day for an Adams, a Leverrier, or a Delaunay. 
Even now a thousand grand problems are presented 
to our men of science which escape their notice; and 
we might as reasonably argue that there must be 
creatures existing unperceived among us, who deal 
with these problems, as that, out yonder in space, 
there must be beings who study the complicated 
motions of the Jovial satellites. 

Jupiter presents the following principal physical 
habitudes: 

He has a diameter of about eighty-five thousand 
miles, or nearly eleven times as large as the earth's, 
a surface one hundred and fifteen times larger, and, 
as I have said, a volume more than twelve hundred 
times larger. Gravity at his surface is about two 
and a half times as great as on our earth's, so that 
such creatures as exist around us would find their 
weight much more than doubled if they were removed 
to Jupiter. He lies more than five times further from 
the sun than our earth, and the light and heat which 
he receives from that orb are reduced to about one- 
twenty-fifth of our supply. He rotates on his axis 
in rather less than ten hours (nine hours, fifty-five 
minutes, twenty-six seconds), so that the length of 
his day is considerably less than half of ours. His 
axis is nearly perpendicular to his orbit, so that 
there are no appreciable seasonal changes as he 
sweeps round the sun in his long year of 4,832% 
days. 



JUPITER, GIANT OF SOLAR SYSTEM 13l 

It will be convenient to consider, first, the prob- 
able influence of the great attractive power of Jupiter 
upon the dimensions of the various orders of living 
creatures existing upon his surface. 

The grandeur of his orb naturally suggests, at 
first sight, the idea of beings far exceeding, both 
in might and bulk, those which live upon the earth. 
Old Wolfius was led to a similar conclusion in an- 
other way. I quote his quaint fancies as quaintly 
presented by Admiral Smyth. " Wolfius,*' says the 
genial sailor, "not only asserts that there are inhabi- 
tants in Jupiter, but also shows that they must nec- 
essarily be much larger than those of the earth; in 
fact, that they are of the giant kind, and nearly 
fourteen feet high by e^e-measurement. And thus 
he proves it. It is shown in optics that the pupil 
of the eye dilates and contracts according to the 
degree of light it encounters. Wherefore, since in 
Jupiter the sun's meridian height is much weaker 
than on the earth, the pupil will need to be much 
more dilatable in the Jovial creature than in the ter- 
restrial one. But the pupil is observed to have a 
constant proportion to the ball of the eye, and the 
ball of the eye to the rest of the body; so that, in 
animals, the larger the pupil the larger the eye, and 
consequently the larger the body. Assuming that 
these conditions are unquestionable, he shows that 
Jupiter's distance from the sun, compared with the 
earth's, is as twenty-six to five; the intensity of the 
sun's light in Jupiter is to its intensity on the earth 
in a duplicate ratio five to twenty-six." The eyes 



< Z0H ' ; — — — __ MIM 



132 OTHER WORLDS THAN OURS 

of the Jovials and their dimensions generally must 
be correspondingly enlarged, and "it therefore fol- 
lows that even Goliath of Gath would have cut but 
a sorry figure among the natives of Jupiter. That 
is, supposing the Philistine's altitude to be some- 
where between eight feet and eleven, according as 
we lean to Bishop Cumberland's calculation, or the 
Vatican copy of the Septuagint. Now, Wolfius 
proves the size of the inhabitants of Jupiter to be 
the same as that of Og, king of Bashan, whose iron 
camp-bed was nine cubits in length and four in 
breadth— or rather he shows, in the way stated, the 
ordinary altitude of the Jovicolae to be 1S#& Paris 
feet, and the height of Og to have been 1BHU feet. 
See his Works, vol. iii., p. 438." 

This exact determination of the dimensions of 
Jovial men would be very pleasing and satisfactory, 
were it not that another line of argument guides us 
at least as conclusively to a very different view. If 
\ we are to assume that beings resembling men in all 

attributes except size, actually exist on Jupiter, we 
might claim for these beings the power of moving 
from place to place as freely as we do, with quite as 
much reason as "Wolfius claimed for them the same 
powers of vision that we possess. Proceeding ac- 
cording to this view, we are led to the conclusion 
that the Jovicolce are pygmies about two and a half 
feet, on the average, in height. For we know that 
a man removed to Jupiter would weigh about two 
and a half times as much as he does on our own 
earth. He would thus be oppressed with a burden 



JUPITER, GIANT OF SOLAR SYSTEM 133 

equivalent to half as much again as his own weight. 
This would render life itself an insupportable bur- 
den; and we have to inquire what difference of size 
would suffice to make a Joveman as active as our 
terrestrial men. Now, the weight of bodies similarly 
proportioned varies as the third power of the height; 
for example, a body twice as high as another — in 
other respects similar — will be eight times as heavy. 
But the muscular power of animals varies as the 
cross- section of corresponding muscles, or obviously 
as the square of the linear dimensions; so that of 
two animals similarly constituted, but one twice as 
high as the other, the larger would be four times the 
more powerful. He would weigh, however, eight 
times as much as the other. He would therefore be 
only half as active. Similarly, an animal three times 
as high as another of similar build would be only 
one-third as active; and so on for all such relations. 
Now, since a terrestrial man removed to Jupiter 
would be two and a half times as heavy as on the 
earth, it follows obviously that a man on Jupiter 
proportioned like our terrestrial men would be as 
active as they are, if his height were to theirs as 
one to two and a half. Hence, setting six feet 
as the maximum ordinary height of men on the 
earth, we see that the tallest and handsomest of 
the Jovicolae can be but two and a half feet in 
height, if only our premises are correct Thus, Tom 
Thumb and other little fellows, if removed to Ju- 
piter, might be wondered at for their enormous 
height, and eagerly sought after by any Carlylian 









134 OTHER WORLDS THAN OURS 

Fredericks who may be forming grenadier corps out 
yonder. 

One line of argument having thus led us to re- 
gard the Jovicolse as Ogs of Bashan, while another 
equally plausible has reduced their dimensions to 
those of our two-year-old children, we may fairly 
conclude that this method of reasoning is fallacious. 
We must not measure the inhabitants of other worlds 
according to the conceptions suggested by the forms 
of life we are acquainted with upon earth. We must 
admit the possibility that arrangements, as different 
from those we are familiar with as the constitution 
of the insect is from that of man, may be presented 
amid the orbs which circle round the sun. It were 
unwise, no doubt, to give free scope to speculation 
where we have in truth no means of forming an 
opinion. We need not imagine, as some have done, 
that "the inhabitants of Jupiter are bat- winged, ' ' or 
with others, "that they are inveterate dancers." Nor, 
to t&ke the views of more respectable authorities, need 
we agree with Sir Humphry Davy, that the bodies of 
the Jo vials are composed of "numerous convolutions 
of tubes more analogous to the trunk of the elephant 
than anything else"; with Whewell, that they are 
pulpy, gelatinous creatures, living in a dismal world 
of water and ice with a cindery nucleus; nor finally, 
with Brewster, that the Jovial may have his "home 
in subterranean cities warmed by central fires, or in 
crystal caves cooled by ocean-tides, or may float with 
the Nereids upon the deep, or mount upon wings as 
eagles, or rise upon the pinions of the dove, that he 



JUPITER, GIANT OF SOLAR SYSTEM 



135 



may flee away and be at rest." So soon as we give 
a definite form to the conceptions that the imagina- 
tion, free from the control of exact knowledge, frames 
respecting the inhabitants of other worlds, we touch 
at once on the grotesque, the hideous, or the ridicu- 
lous. 1 It is sufficient to recognize the probability, 
or rather the certainty, that the beings of other 
worlds are very different from any we are acquainted 
with, without endeavoring to give shape and form to 
fancies that have no foundation in fact. 

We may regard it as probable, however, that liv- 
ing creatures in Jupiter, if any exist, are built gener- 
ally on a much smaller scale than those which people 
our earth. Trees, plants, and the vegetable world 
generally, must also, one would imagine, be very 
differently constituted from those we are familiar 
with. It is well known that the motion of the veg- 
etable juices is in part regulated by the force of 



1 It may be worth while to gather a lesson from this circumstance. 
We know that every form of life is replete with evidences of adapta- 
tion (no matter how secured) to the conditions which surround it. We 
have thus evidenced to us, as forcibly as possible, the perfection of the 
laws by which the Creator rules the universe, and a measure (if one 
may so speak) even of that which is inconceivable by us — His infinite 
wisdom. Now, man, with all his knowledge of the Creator's ways, 
yet so soon as he passes the boundary of the known, pictures to him- 
self all manner of unnatural and impossible forms of existence. Even 
the unknown parts of our own earth have been peopled ere now, in im- 
agination, with "men whose heads do grow beneath their shoulders,*' 
and other similarly incongruous beings. It is more excusable, perhaps, 
that an anatomically impossible structure should have been assigned to 
angels (the cherubim have been even more unfortunate), while the Evil 
One, that "goeth about as a roaring lion," has had the principal at- 
tributes of a class of ruminantia assigned to him. 



136 OTHER WORLDS THAJS, OURS 

gravity, and therefore it must be admitted that the 
structure of terrestrial plants is in part dependent 
upon the value of gravitation at the earth's surface. 
Whewell, in his "Bridgewater Treatise* ' on the astro- 
nomical evidence of design in Creation, lays great 
stress on this relation, pointing out, if 1 remember 
right, that all vegetation would be destroyed at once 
if there could suddenly take place any marked change 
in the earth's attractive forces. If this view is cor- 
rect, it is certain that none of our plants could thrive 
on the soil of Jupiter. 

The year of Jupiter differs in a much more strik- 
ing manner than that of Mars from our terrestrial 
year. It consists of nearly twelve such years as ours, 
so that the period corresponding to one of our seasons 
lasts nearly three years, and a Jovial month is nearly 
equal to one of our terrestrial years. He has, how- 
ever, no seasons in our sense of the word, since his 
equator is inclined but little more than three degrees 
to his orbit. Thus a perpetual spring reigns all over 
his surface. 

But before we proceed to form a high opinion of 
the planet's condition under the influence of this per- 
petual spring, let us distinctly understand what the 
words mean. The word spring has a genial sound to 
ourselves, because we associate it with that which is 
commonly the pleasantest portion of our year; but it 
is just possible that the perpetual spring reigning over 
Jupiter, though doubtless well adapted to the wants of 
his inhabitants, leads to a state of things such as we 
might not tind altogether so agreeable. 



JUPITEH, GIANT OF SOLAR SYSTEM 137 

Admiral Smyth says that "as the rays of the sun 
fall perpendicularly on the body of the planet, 1 and 
always continue to do so, the heat must be as nearly 
as possible equal at all times of the year — a perennial 
summer: this is a striking display of beneficent ar- 
rangement.' * But we must be cautious in adopting 
this mode of argument in dealing with the Creator's 
ways. That the arrangement is beneficent, we need 
not of course question. But that we can recognize 
the way in which it is beneficent is quite another 
matter. If Jupiter's great distance from the sun is 
compensated for by this peculiar disposition of his 
axis, and we are to admire the beneficence thus dis- 
played, are we therefore to find fault with the Cre- 
ator for not dealing similarly with Saturn, Uranus, 
and Neptune, which, being further from the sun, 
hare greater need than Jupiter of some special adap- 



1 la the same paragraph Admiral Smyth says that, as seen from 
Jupiter's equatorial regions, the sun would seem to move through the 
heavens with great rapidity, while near the polar regions the sun's mo- 
tion will be comparatively slow, and he will be seen to describe only a 
small semicircle above the horizon. The direct reverse is, however, the 
case, the sun's path and the rapidity of his apparent diurnal motion 
being nearly constant for all parts of Jupiter, and throughout his 
year. Admiral Smyth seems to have thought that the variations of the 
sun's path in Jupiter corresponded to those observed in the progress of 
a year at any place on the earth's equator, the sun always rising verti- 
cally and always describing a complete semicircle, though attaining dif- 
ferent altitudes a* different seasons. The real fact is, that in all parts 
of Jupiter the sun describes a complete diurnal semicircle, attaining a 
different midday altitude in different places. But, as he always rises 
nearly due east, and sets nearly due west (as he does in spring-time all 
over the earth), he necessarily crosses the horizon at different angles as 
seen in different places, and always describes about half of a great 
circle of the sphere. 



138 OTHER WORLDS THAN OURS 

tation of the sort? It seems safer to consider the 
consequences which flow from the arrangement with- 
out any special reference to the design of the Creator 
in permitting them, lest, in our over-anxiety to rec- 
ognize beneficence in the treatment of one world, we 
should adopt a mode of reasoning which leads to the 
direct conclusion that other worlds have been ill- 
cared for. 

The great peculiarity resulting from the arrange- 
ment in question — the only peculiarity, in fact, of 
which we can speak with any confidence — consists in 
this, that, everywhere on Jupiter, day and night are 
of equal length. It is in this sense only that per- 
petual spring — or perpetual autumn, if we please— 
reigns on the giant planet. The different latitudes 
of Jupiter have climates differing quite as much as 
those found in different latitudes on our own earth. 
At the equator the sun passes every day nearly to 
the point overhead. At the poles the sun seems to 
glide along the horizon, rising in the east, passing 
round — always near the horizon — toward the south, 
and thence to his setting-place in the west. In in- 
termediate latitudes, the sun passes to a southerly 
elevation which is greater or less, according as the 
place is nearer to or further from Jupiter's equator. 
It follows that there is a marked difference between 
the sub-equatorial and the sub-polar regions in Jupi- 
ter, while between these regions every intermediate 
climate is to be found. 

Owing to the rapidity of Jupiter's rotation, the 
motion of the sun in the Jovial sky must be much 



_ 



JUPITER, GIANT OF SOLAR SYSTEM 139 

more readily discernible and measurable than that 
with which the sun seems to pass across our own 
heavens. He traverses the whole semicircle, from 
the eastern to the western horizon, in two minutes 
less than five hours, or about six degrees in ten 
minutes. This corresponds to a motion through a 
space equal to the sun's diameter (as we see him) in 
fifty seconds, and must be readily discernible, even 
to the unaided vision of the Jovicolse, unless their 
eyesight is much inferior to ours. The smallness of 
the sun, as seen from Jupiter, must help to render 
the motion more perceptible. He presents to them 
an apparent diameter only equal to about one -fifth 
of that with which we see him, so that in ten sec- 
onds he seems to pass over a space equal to his own 
diameter. 

The other celestial bodies are affected with similar 
motions as seen from Jupiter. Of course, those seen 
near the poles of his heavens seem relatively at rest. 
One of these poles lies in the heart of the constella- 
tion Draco; the other lies close by the great Magel- 
lanic Cloud, which must present a magnificent cyno- 
sure to the inhabitants of the southern hemisphere 
of the planet. The contrast between the steadfast- 
ness of the polar star-groups and the swift motions 
of the equatorial constellations must be impressive 
indeed. These equatorial groups are no other than 
our old friends the zodiacal constellations. As seen 
by the inhabitants of Jupiter, they rise with a per- 
ceptible but stately motion above the eastern horizon, 
pass to their culmination on the southern meridian, 



140 OTHER WORLDS THAN OURS 

and so to their setting place in the west — exhibiting 
the same splendors which the terrestrial astronomer 
delights to gaze upon, enhanced by the peculiar im- 
pressions of active power suggested by visible and 
obvious motion. 

It may seem, at first sight, that the presence of 
the Jovial satellites must tend to dim the splendor 
of the sidereal heavens. Our own moon, despite 
the beautiful passage 1 in which Homer has described 
the calm beauty of a moonlit night, certainly de- 
tracts largely from the magnificence of the star- 
groups; and as at times there must be four moons 
visible above the horizon of the Jovials, it might 
seem that all but the brighter stars would be quite 
obliterated. The first moon must appear somewhat 
larger than our own; the next has an apparent di- 
ameter rather more than half as large as that of our 
moon; the third (really the largest) appears about as 
large as the second; and the fourth has an apparent 
diameter equal to about a quarter of our moon's. 
Thus, in all, they cover a space on the sky more 
than half as large again as that which our moon 
covers. But, in reality, they cannot have nearly so 
marked an effect in dimming the lustre of the stars. 
For it must not be forgotten that they shine only by 
reflecting the sun's light, and that he illuminates 



1 Homer must not be held responsible for Pope's amazing descrip- 
tion, which, strangely enough, has found an ardent admirer in one of 
our best modern observers. Homer did, however, mention, as a char- 
acteristic of the moonlit sky, that "all the stars shine," a proof that 
sometimes, as Horace tells us, the great master nodded. 



JUPITER, GIANT OF SOLAR SYSTEM 



141 



them but faintly, in comparison with the light he 
pours upon our own moon. In effect, supposing 
their reflective capacities equal to the moon's, they 
must appear less brilliant than she does, in the pro- 
portion of about one to twenty-five; and combining 
this result with the above relation, it follows that, 
even if they could all be "full" together, they could 
send to the Jovials but about one-sixteenth part of 
the light we receive from the full moon. But, as a 
matter of fact, they cannot all be full together. The 
motions of the inner three are so related, that, though 
there is nothing to prevent them from being all visi- 
ble together, 1 yet, when so visible, one only can be 
full. The fourth may be full at the same time r or, 
in fact, may be combined with the other three in 
any way, since its motions are not bound up with 
theirs as theirs are inter se. 

Even now, however, we have not reached a full 
estimate of the extent of the mistake which those as- 
tronomers have made who speak of the splendor with 
which the satellites of Jupiter illuminate his skies. 
When at that part of their orbits where they would 
otherwise be full, the three inner moons are always 
eclipsed, and though the fourth, by reason of its great 
distance, 2 sometimes escapes eclipse, yet more fre- 
quently it is obscured like the others. The two in- 

1 Or all invisible together. Lardner asserts the contrary ; so that 
one would imagine he had never seen all the moons together on the 
same side of Jupiter. 

2 Not on account of the inclination of its orbit being large, as Sir 
John Herschel has said. The orbit of this satellite is, indeed, less in- 
elined than the orbits of the others. 






142 OTHER WORLDS THAN OURS 

ner satellites are eclipsed for upward of two hours, 
and as they occupy but a few hours in completing 
their circuit round the sky, 1 it will be seen how 
largely this relation detracts from their light-supply- 
ing powers. 

We see, then, that those writers have been mis- 
taken who allege that the great distance of Jupiter 
from the sun is compensated by the number of his 
moons, and the quantity of light they reflect toward 
him. So far is this from being the case, that, under 
the most favorable circumstances, they can supply 
during the Jovial night but about one-twentieth part 
of the light with which the full moon illuminates our 
nocturnal skies. The poetical descriptions which im- 
aginative writers have indulged in, respecting the 
splendor of the scene presented by these satellites, 
will not bear the dry light of numerical estimation. 
That the satellite-system of Jupiter subserves impor- 
tant functions, and affords, in reality, like all the 
works of the Creator, the amplest evidence of design, 
need not be questioned; but that we have been able 
to understand the special purpose for which they 
have been created — in fine, "to see," as the Creator 
does, "that they are good" — may be assuredly denied. 

Perhaps, if one were able to discuss with advan- 
tage the special purposes which this or that portion 
of creation is intended to subserve, it might be argued 
that the outer planets have greater need of moons than 

1 Moving in a direction contrary to that due to the rotation of Jupi- 
ter, they of course remain longer above the horizon than the sun, or 
the equatorial fixed stars. 



JUPITER, GIANT OF SOLAR SYSTEM 



143 



the inner, because, their year being longer, there is 
greater occasion for objects whose motions shall serve 
as measures of time. The satellites of Jupiter supply, 
by their separate motions, convenient measures of the 
shorter time -intervals; while, by their successive con- 
junctions, (1) in pairs, (2) the three inner together, 
and (3) the outer with pairs of the inner, they afford 
convenient measures of longer intervals. 

But let us turn from vague guesses at the pur- 
poses of the Almighty to the consideration of those 
facts which are actually presented to our notice. 

Eecognizing the existence of varied climatic rela- 
tions in different parts of Jupiter, we have now to 
consider the climate of the planet generally, to con- 
template the position of this great orb in the solar 
system, and to determine how far its great distance 
from the sun may be compensated by other relations. 

There can be no doubt that the amount of heat 
poured by the sun on any portion of Jupiter's sur- 
face, placed perpendicularly with respect to the heat- 
rays, must be very much less than the amount 
received by an equal portion of our earth's surface, 
similarly situated. The direct heating effects of the 
sun must, in fact, as already stated, be less on Jupiter 
than on our own earth, in the proportion of about 
one to twenty-five. And it cannot be doubted that 
the effects of this difference must be highly important, 
whatever arrangements may exist to compensate for 
the deficiency of heat. If we can demonstrate in any 
way that the mean temperature of the Jovial atmos- 
phere is equal to that of our own air, or even greater,. 



\ 



144 OTHER WORLDS THAN OURS 

yet the difference of the sun's direct heat involves a 
variety of consequences which we cannot disregard. 

We know, for instance, that it is principally the 
direct heat of the sun that causes the evaporation of 
water from the surface of oceans, seas, lakes, and 
rivers, and therefore all the important consequences 
which flow from the presence of aqueous vapor in 
large quantities in the earth's atmosphere. We can 
conceive the existence of vapors in the air which 
might keep away from the earth's surface the greater 
portion of the sun's heat, and yet, by preventing the 
escape of the remainder by radiation into space, might 
leave the general warmth of the air around us as 
great as it is at present. But it cannot be doubted 
that such an arrangement would injuriously affect the 
whole economy of evaporation and its consequences, 
winds, rains, clouds, mist, with their consequences, 
so important for the welfare of terrestrial races. 

And in like manner other effects accruing from the 
direct action of the solar rays might be considered. 

It follows, then, that it is by no means sufficient 
to show how the heat which falls upon Jupiter may 
be stored up, through the action of some component 
of his atmosphere in preventing its radiation into 
space. It is, indeed, of the utmost importance to 
know that even this is possible, because we are thus 
enabled to see that Jupiter is not necessarily an 
abode so bleak and desolate as some writers have 
imagined. In the following passage, Professor Tyn- 
dall has exhibited the means by which this result 
may be brought about, and the inhabitants of the 



JUPITER, GIANT OF SOLAR SYSTEM 145 

noblest planet in the solar system placed somewhat- 
higher in the scale of creation than Whewell sur- 
mised. "In these calculations," he remarked, refer- 
ring to WhewelTs estimate of the suns heating 
power on Jupiter and the other exterior planets, 
44 the influence of an atmospheric envelope was over- 
looked, and this omission vitiated the entire argu- 
ment. It is perfectly possible to find an atmosphere 
which would act the part of a barb to the solar rays, 
permitting their entrance toward the planet, but pre- 
venting their withdrawal. For example, a layer of 
air, two inches in thickness, and saturated with the 
vapor of sulphuric ether, would offer very little re- 
sistance to the passage of the ether rays, but I find 
that it would cut off fully thirty-five per cent of the 
planetary radiation. It would require no inordinate 
thickening of the layer of vapor to double this ab- 
sorption; and it is perfectly evident that, with a pro- 
tecting envelope of this kind, permitting the heat to 
enter but preventing its escape, a comfortable tern 
perature might be obtained on the surface of our 
most distant planet." The difference between such 
an arrangement as this and the way in which the 
earth's temperature is obtained, is the exact converse 
of that dealt with when we were considering the 
case of Mercury and Venus. Precisely as the mean 
temperature of the atmosphere of either of the in- 
terior planets may be no higher than that of our own 
air, while yet the sun's direct rays continue wholly 
unbearable, so the outer planets may have a per- 
fectly comfortable temperature, while yet that direct 
Science — 1 — 7 



146 OTHER WORLDS THAN OURS 

solar heat which exerts so many important influences 
on the earth must be supplied only in quantities which 
we should find wholly inadequate for our wants. 

I am far from desiring to infer that Jupiter must 
therefore be uninhabited, or even that the creatures 
existing on his surface must necessarily differ wholly 
in their nature from any with which we are familiar. 
But I think that, while, on the one hand, we must 
reject one of the chief arguments by which Whewell 
was led to people Jupiter with cartilaginous and 
glutinous creatures (!) floating in boundless oceans, 
so, on the other, we cannot accept without question 
the argument by which an effort has been made to 
indicate the possibility of a close correspondence be- 
tween Jupiter's climate and our earth's. 

And here we are led to the most interesting and 
suggestive of all the relations exhibited by Jupiter, 
or rather to three closely-associated relations, which 
lead to views of a somewhat startling character. 

In common with the other large planets lying out- 
side the zone of the asteroids, Jupiter has a mean 
density falling very far short of the mean density 
of the earth or the other small planets which travel 
within that zone. According to the best estimates 
of his mass and apparent diameter, his mean density 
would seem to be rather less than one-fourth of the 
earth's, or greater than the density of water by 
about one-third. It is worthy of remark, in fact, 
that his density is almost exactly the same as the 
sun's, and considerably greater than that of the 
other three outer planets hitherto discovered. 



JUPITER, GIANT OF SOLAR SYSTEM 147 

If we were quite certain that the disk measured 
by us exhibits the real outline of the planet, or 
that his atmosphere was not of abnormal extent, and 
that his globe was solid throughout, it would follow 
that the substances composing Jupiter were either 
altogether different from those forming our earth, 
or that they were combined in very different propor- 
tions. On the last point we can form no opinion. 
On the first we must be guided by the appearance 
of the planet. 

Thus we are led to the second of the three rela- 
tions just mentioned — the appearance of well-marked 
but variable belts on the planet — and of other indica- 
tions implying the existence of an atmosphere of 
great extent. 

The belts of Jupiter are commonly arranged with 
a certain symmetry on either side of the great equa- 
torial bright belt, but sometimes there is a rather 
marked contrast between the northern and the south- 
ern halves of the planet. In color the dark belts 
are usually — when seen with suitable telescopic pow- 
er 1 — of a coppery, ruddy, or even purplish tint, 
while the intermediate light bands vary from a 
pearly white in the equatorial belt, through yellow- 
ish white in the middle latitudes of both hemi- 



1 What is required is not so much a high light-gathering as a high 
magnifying power, though both points are of importance. When the light 
is not adequately reduced by increase of magnifying power, the color is 
lost in the resulting "glare." Reflectors seem to have an advantage over 
refractors in exhibiting the colors of the planets ; at least, nearly all the 
accounts in which the appearance of color has been specially dwelt upon 
have been received from observers who have used reflectors. 



145 OTHER WORLDS THAN OURS 

spheres, to a grayish or even bluish tint at the 
poles. 

There is every reason to believe that these belts 
indicate the existence of a very extensive vapor- 
laden atmosphere. The dark belts must not be con- 
sidered as the true cloud-belts, because it must be 
remembered that we look upon the reverse side of 
the skyscape presented during the day to the Jovi- 
als: so that where they see densely-compacted dark 
clouds, we see the light which those clouds have in- 
tercepted; and, on the other hand, where they see 
clear spaces, the light which reaches them is not re- 
flected to us without a considerable loss of brilliancy. 
Thus the dark belts of Jupiter are those regions 
where — if at all — we see the true surface of the 
planet. 

Now, viewing the belts in this light, have we any 
means of judging from their aspect what is the ex- 
tent of the planet's atmosphere? So far as I know, 
the question has never been considered, but it is well 
worthy of careful study. 

It seems clear, in the first place, that if the bright 
belts really are cloud-belts, and the dark belts the 
surface of the planet, then on the edge of the plan- 
et's disk we ought to see some irregularity of level 
— the cloud-belts projecting slightly beyond the real 
outline of the planet — if the atmosphere have that 
enormous extent which some astronomers have sup- 
posed. Whether such an appearance has ever been 
looked for I do not know, but it has certainly never 
yet been detected. 



JUPITER, GIANT OF SOLAR SYSTEM 



149 



We are forced to conclude, then, that either the 
atmosphere of Jupiter is not sufficiently extensive 
to interfere appreciably with our measurement of the 
planet's bulk, or else the dark belts belong but to a 
lower cloud-layer, not to the planet's real surface. 

We have further evidence on this point in the 
appearance of dark spots on the dusky belts. These 
spots have even been described as black, though sure- 
ly their appearing of that hue must be ascribed to the 
effect of contrast. Now, these dark spots, which 
have been seen by Cassini, Madler, Schwabe, Airy, 
and others, may be regarded as the real surface of 
the planet (unless they belong to a yet deeper cloud- 
layer), seen for a while through openings in the 
cloud-bed to which the dusky belts belong. The 
reader will not fail to notice here some resemblance 
to what has been already mentioned respecting the 
sun-spots; and when we come to the third and most 
striking of the associated features I am now dealing 
with, it will be seen that there may be more in the 
analogy than one might at first sight be disposed to 
imagine. 

How far the appearance of small round white 
spots on the dark belts may be considered as indica- 
tive of the extent and constitution of the Jovial 
atmosphere, it is not very easy to determine. That 
they are dense clouds, hanging suspended above the 
dusky cloud-layer, must be admitted as highly prob- 
able, but it is open to question whether they have 
formed there in the same way that cirrus -clouds are 
seen to form at a great elevation above a layer of 






150 OTHER WORLDS THAN OURS 

cumulus-clouds, or whether they indicate the action 
of volcanoes beneath the dusky layer, propelling 
enormous streams of vapor through the superincum- 
bent cloud-beds. 

The third point on which I have to dwell is the 
variability of the belt-system, under which head I 
include not only variations in shape and extent, but 
those much more significant changes of color which 
have been recently discovered. 

So far as is yet known, there is no recognizable 
law in the changes of shape exhibited by the belts 
of Jupiter — no periodicity or intelligible sequence. 
It may be suggested, in passing, that a systematic 
and persistent scrutiny of the planet might lead to 
the discovery of laws of this sort, which could not 
fail to indicate physical conclusions of the utmost 
importance. Nay, further, since we cannot doubt 
that the condition of the real surface of Jupiter is 
in some sort reflected, so to speak, in the aspect of 
his cloud-envelopes, it seems far from unlikely that 
a scrutiny of this sort might tell us where his oceans 
and continents, where his deserts, lakes, or rivers, 
are situated, even though no direct evidence of their 
existence might ever reward the observer. In these 
days, however, nine-tenths of those who are fort- 
unate enough to possess fine telescopes prefer either 
to leave them idle, or to employ their powers in 
making observations, at great pains and labor, which 
are not worth the paper on which they are recorded. 1 

1 It is painful to those who know what might be done in the numerous 
fine observatories now existing throughout England, to see the powers of 



JUPITER, GIANT OF SOLAR SYSTEM 



151 



The few original observers we have are overtasked 
by the multitude of questions of interest presented 
to their consideration, so that many subjects of in- 
quiry must perforce wait, either till their turn 
arrives, or till those who have the means of study- 
ing them choose to turn their thoughts from the 
sterile subjects they are now engaged upon. 

So far, then, as inquiries have as yet been 
pushed, all that can be asserted on the subject we 
are considering is, that the planet's belts vary 
greatly in form, extent, and general appearance. At 
one time the dusky belts cover a large proportion 
of the planet's disk, at another they are singularly 
narrow. Now they are very regularly disposed, now 
they seem in some way under the action of disturb- 
ing forces of great intensity, causing them to assume 
the most irregular figure. The accompanying picture 
of the planet (Fig. 1) as seen by Mr. Browning, with 



many noble instruments — the chef-d'cetivres of English and Continental 
opticians — devoted to puny imitations of the work done at Greenwich and 
other similar establishments. I speak on the authority of one of the first, 
if not the very first, of our professional astronomers, when I say that these 
imitations, even though they approached in character — which they do not 
and cannot — the operations superintended so ably by the Astronomer 
Royal, would be a simple waste of time and labor. Nor is this the only 
way in which fine telescopes are wasted. While on every side there are 
subjects of research which most pressingly require investigation, many of 
those who possess the requisite means and leisure for the purpose — nay, 
are not wanting in the necessary taste for observational research — are un- 
happily applying themselves to going over, perhaps with relatively inferior 
powers, ground which has already been thoroughly ransacked by our great 
observers. With some ten or twelve exceptions — which it is unnecessary 
to name— our private observatories seem to have banished everything 
resembling originality. 



152 



OTHER WORLDS THAN OURS 



one of his own reflectors, indicates an appearance no* 
uncommonly seen, a dark streak extending obliquely 
across the planet's equatorial regions. The number 
of belts is singularly variable. Sometimes only one 
has been seen, at others there have been as many as 
five or six on each side of the planet's equator. In 




¥t&. 1.— The Planet Jupiter (Browning). 

the course of a single hour, Cassini saw a complete 
new belt form on the planet, and on December 13, 
1690, two well-marked belts vanished completely, 
while a third had almost disappeared in the same 
short interval of time. 

But if we seem to recognize here the action of 
forces much more intense than those which influence 
the condition of the earth's atmosphere, we have still 



JUPITER, GIANT OF SOLAR SYSTEM 153 

more striking evidence to the same purpose in the 
changes of color which have recently been detected 
in the great equatorial belt. This belt is usually of 
a pearly white tint, and has long been recognized as 
one of the most constant features of the planet's 
aspect. As the mean surface of this belt cannot be 
less than a fifth of the whole surface of the planet, 
it is clear that any changes which may take place 
in its general aspect cannot but be of the utmost 
significance. Now, during the autumn of 1869 and 
the spring of 1870, this belt has been more strongly 
colored than any part of the planet. Mr. Browning, 
observing Jupiter in the earlier part of the above- 
named interval, found the equatorial belt of a green- 
ish-yellow color, which deepened in October, 1869, to 
a full ochreish yellow, and in January of the present 
year had assumed an even darker tint, resembling 
yellow ochre. On one occasion, and on one only, 
he detected this tint in the first bright belt north 
of the equator. While thus exhibiting strongly- 
marked and changing colors, the equatorial belt has 
lost its right to be called, par excellence, the bright 
belt of the planet, being considerably inferior in 
brilliancy to the narrow bright belts north and south 
of it. 

Other observers have also seen these colors. Mr. 
Slack, with a 6-inch Browning-With reflector, and 
Mr. Brindley, with an 8^ -inch telescope of the same 
construction, have witnessed most of the changes of 
color above described ; and I myself, using Mr. 
Browning's 124-inch telescope, found the greenish- 



154 OTHER WORLDS THAN OURS 

yellow tint of the equatorial belt last autumn alto- 
gether unmistakable. 1 

In the phenomena here described we have a prob- 
lem whose interpretation is far from easy. Changes 
in the shape, disposition, and extent of the dark 
belts are sufficiently intelligible when we associate 
them, as we seem justified in doing, with variations 
in the position of the currents which traverse the 
vaporous envelope of Jupiter as the trades and 
counter -trades traverse the earth's atmosphere. But 
the equatorial zone is Jupiter's belt of calms, re- 
sembling in this respect the equatorial region, called 
by sailors the " doldrums," and, though occasional 
storms might be expected to agitate this region, yet 
processes of change, continuing for several months 
in succession, can evidently not be attributed to any 
such cause. We are taught, by the progress of re- 
cent research, to regard the color of the light derived 
from any source as a relation of the most instructive 
character, and changes of color, especially changes 
affecting so enormous a body as Jupiter, and so ex- 
tensive a proportion of his surface, cannot but be 
looked upon as highly significant. Supposing we 
regard the ordinarily white light of the equatorial 
belt as indicative of the existence of enormous 



1 I had written thus far only, when I attended the meeting of the Royal 
Astronomical Society on January 14, 1870, where Mr. Buckingham, the 
owner of the great refractor, 2l£ inches in aperture, from whose perform- 
ance so much was expected, mentioned that, as seen with this powerful 
instrument, the great belt was resolved into a number of small colored 
clouds on a white ground. 



JUPITER, GIANT OF SOLAR SYSTEM 155 

masses of cloud reflecting ordinary solar light to us, 
then we should have to regard the appearance of any 
other color over this region as an indication that 
these cloud-masses had been, through some unknown 
cause, either wholly or in part swept away. But — 
passing over the objection that this view leaves our 
difficulty unexplained — even if we assumed that in 
this way a portion of the surface of Jupiter had been 
brought into view, wholly or partially, why should 
this surface not exhibit a constant appearance? We 
cannot suppose changes affecting Jupiter's real sur- 
face are taking place with sufficient rapidity to ex- 
plain the series of strange color-changes observed 
by Messrs. Browning, Slack, and other astronomers. 
But if, on the other hand, we assume that a portion 
of the light ordinarily received from the bright belt 
is inherent — that is, that the planet is, to some ex- 
tent, self-luminous — then there remains the difficulty 
of explaining by what conceivable processes the 
equatorial regions are filled with a yellow light, so 
full and bright as to reach our earth from beyond 
four hundred millions of miles. 

But I have spoken of the three relations last con- 
sidered — the small density of Jupiter, his extensive 
atmosphere, and the changes which take place in the 
shape and color of his belts — as associated phenomena. 
It remains that I should endeavor to justify this state- 
ment. 

We know that Whewell, reasoning from the low 
specific gravity of Jupiter, was led to the conclusion 
that either the substance of the planet is wholly 



/ 



156 OTHER WORLDS THAN OURS 

watery, or eke a few cinders in the centre of Jupi- 
ter's globe constitute the only solid portion of his 
substance. It need hardly be said that the whole 
progress of modern astronomy is opposed to this 
view. We have seen that in the sun the same ele- 
ments exist as in the earth, and that in the only 
planet whose nature we have been able to examine 
satisfactorily we find evidence of the existence of the 
same forms of matter that we see around us. It can- 
not but be held as highly improbable that the earth 
is the only member of the planetary system whose 
substance thus closely resembles that of the parent 
orb, nor is it likely that Mars is the only planet 
whose general atmospheric constitution resembles the 
earth's. Far more probably the lesson we are really 
to learn from these circumstances is, that throughout 
the solar system a general similarity of constitution 
exists, the sun being, so to speak, the type of the 
family over which he rules. Differences of condition 
we are compelled to recognize, since the sun itself, 
though constituted of the same elements as the earth, 
is in so different a state and has a mean density rela- 
tively so small; but we have no evidence justifying 
us in believing that any important differences of con- 
stitution exist throughout the solar system. 

Thus, we are led to regard the singularly small 
density of Jupiter, and of the other planets outside 
the orbits of the asteroids, as due rather to some 
peculiarity in the condition of these orbs than to 
any such peculiarity of structure as W he well in- 
sisted on. It will be seen at once that Jupiter's ex- 



JUPITER, GIANT OF SOLAR SYSTEM 157 

tensive atmospheric envelope and the strange changes 
in the aspect of his belts are circumstances which 
tend strikingly to confirm this impression. Let it be 
remembered that, supposing Jupiter's globe even to 
be wholly covered with water, yet a sun twenty five 
times further off than ours could not by any possi- 
bility load his atmosphere with the enormous masses 
of vapor actually present in it. Let it be remem- 
bered, further, that the relatively sluggish action of 
the sun upon Jupiter could not by any possibility 
give rise to atmospheric disturbances so tremendous 
as those which are evidenced by the rapid changes 
of figure of his cloud- bands. 1 When to this we add 
the relative minuteness of the seasonal changes on 
Jupiter, we see at once that, unless some other cause 
than solar action were at work, the condition of Jupi- 
ter's atmosphere ought to be very much calmer than 
that of the earth's* 

It seems to me that these considerations point 
with tolerable clearness to the conclusion that, within 
the orb which presents so glorious an aspect upon 
our skies, processes of disturbance must be at work 



1 It is worthy of consideration, also, that even though the win acted 
as efficiently upon the air and oceans of Jupiter (assumed to be similar 
to our own), yet atmospheric disturbances (due chiefly, as we know, to 
these two forms of action) could not possibly be so violent even as on 
our own earth, since corresponding latitudes of Jupiter (that is, regions 
where corresponding effects would be experienced) are separated by dis- 
tances so very much greater. It is clear that, if along a certain zone of 
a planet the sun exerts a certain amount of influence, while along an- 
other he exerts a different influence, the result of the difference, looked 
on as a cause of atmospheric disturbance, must be smaller as tbe dis- 
tance between the zones is greater. 



/ 



158 OTHER WORLDS THAN OURS 

wholly different from any taking place on our own 
earth. That enormous atmospheric envelope is loaded 
with vaporous masses by some influence exerted from 
beneath its level. Those disturbances which take 
place so frequently and so rapidly are the evidences 
of the action of forces enormously exceeding those 
which the sun can by any possibility exert upon so 
distant a globe. And if analogy is to be our guide, 
and we are to judge of the condition of Jupiter ac- 
cording to what we know or guess of the past condi- 
tion of the earth and the present condition of the 
sun, we seem led to the conclusion that Jupiter is 
still a glowing mass, fluid probably throughout, still 
bubbling and seething with the intensity of the pri- 
meval fires, sending up continually enormous masses 
of cloud, to be gathered into bands under the influ- 
ence of the swift rotation of the giant planet. No 
otherwise, as it seems to me, can one explain the in- 
tense vitality, if one may use the expression, of a 
planet circumstanced as Jupiter is. No otherwise can 
one understand whence his atmosphere is loaded with 
vapor-masses whose contents must exceed, on a mod- 
erate computation, all the oceans on the surface of 
this earth. When we see masses so enormous swayed 
by influences of such energy, that intermediate belts, 
thousands of miles in width, are closed up in a single 
hour; 1 when we recognize the tremendous character 



1 Even if we take the disappearance of a dark belt to be due to the 
formation of clouds, which is perhaps more probable than that the clouds 
of neighboring belts have closed in, the forces represented by the change 
are nevertheless tremendous. 



JUPITER, GIANT OF SOLAR SYSTEM 159 

of the motions which, from beyond four hundred 
millions of miles, are distinctly cognizable by our 
telescopes, we see that we have no ordinary phenom- 
ena to deal with, and that the theory we adopt for 
their explanation cannot be otherwise than striking 
and surprising. 

If the view which I have here put forward — or 
rather, the view to which I have been led by a care- 
ful consideration of the phenomena which Jupiter 
presents to our contemplation — be indeed correct, we 
must of course dismiss the idea that the giant planet 
is at present a fit abode for living creatures. Yet 
need we not turn from his system with the thought 
that here at least our hopes of recognizing other 
worlds have been disappointed. If Jupiter be still 
in a sense a sun, not indeed resplendent like the 
great centre of the planetary scheme, but still a 
source of heat, is there not excellent reason for be- 
lieving that the system which circles aroiznd him 
consists of four worlds where life— even such forms 
of life as we are familiar with — may still exist? 
Those four orbs, which our telescopes reveal to us 
as tiny points of light, are in reality globes which 
may be compared with the four worlds that circle 
nearest to the sun. I have shown that they cannot 
subserve the purpose which many astronomers have 
ascribed to them, of compensating Jupiter for the 
small amount of light he receives, even if they could 
be seen from any point of his cloud-encompassed sur- 
face. So that, even adopting the commonplace and 
superficial view that the purpose of any object may 



! 



/ 



160 OTHER WORLDS THAN OURS 

be regarded as ascertained when we have been able 
to ask (without any obvious answer) what other pur- 
pose it can subserve, we still are led to the belief 
that the satellites of Jupiter must be the abode of 
life, since on this view, and on this view only, we 
find a raison d'etre both for the planet and for the 
system which circles around him. 

There are no considerations which appear directly 
opposed to the view that Jupiter is in a sense a 
sun. It need hardly be said that I do not regard 
him as being in the same condition as the central 
luminary of the planetary system. He is not an 
incandescent body, or, if he is, the greater part of 
his light is veiled by the cloud -envelopes which sur- 
round him. The solar clouds are, as we know, them- 
selves luminous; those of Jupiter are not so, a cir- 
cumstance which indicates that the heat of Jupiter 
is not sufficient to vaporize those substances which 
are incandescent when in the liquid state. The 
outer layer of clouds must, therefore, be regarded as 
for the most part aqueous. We see there, in fact, 
the future oceans of Jupiter, if the hypothesis I am 
now dealing with be correct. 

That Jupiter may supply an immense amount of 
heat to his satellites (on this view of his condition) 
is perfectly clear, since the amount of light he emits 
is no adequate measure of the amount of obscure 
heat which radiates from him to the four worlds 
around him. When we consider the enormous ap- 
parent size of Jupiter as seen from his satellites, we 
recognize at once how large a supply of heat he is 



JUPITER, GIANT OF SOLAR SYSTEM 161 

capable of transmitting to them. From the outer- 
most satellite his apparent diameter exceeds that of 
the sun (as seen by us) some eightfold, and his ap- 
parent size, therefore, exceeds the sun's more than 
sixty-fold. From the innermost he is seen with a 
diameter nearly forty times that of the sun, and with 
an apparent area more than fourteen hundred times 
as large as his. 

We have evidence, however, which renders it far 
from improbable that Jupiter may emit some small 
proportion of light. I have already referred to the 
singular excess of his brilliancy over that due to his 
size and his distance from the sun and from us* 
The estimates of Zollner, the eminent photometri- 
cian, serve to show, not, indeed, that Jupiter sends 
more light to us than he receives from the sun, but 
that he sends much more light than a planet of 
equal size and constituted like Mars, the moon, or 
the earth, could possibly reflect to us if placed where 
Jupiter is. Whereas Mars reflects but one-fourth of 
the light he receives, Jupiter reflects more than 
three-fifths. The moon sends less than a fifth; Sat- 
urn, Jupiter's brother giant, more than a half. The 
late Professor GK Bond, of America, actually calcu- 
lated that Jupiter sends forth more light than he re- 
ceives. Whether his observations or the more sys- 
tematic observations of the German astronomer are 
accepted, we see that, unless we adopt some such 
hypothesis as I have dealt with above, we must rec- 
ognize a marked difference between the relative light- 
reflecting capacities of the two largest planets of the 



i 

i 



162 OTHER WORLDS THAN OURS 

system, and those of Mars or the moon. In fact, 
from other researches of Dr. Zollner's it follows that, 
if Jupiter does not shine in part by native light, his 
surface must possess reflective powers nearly equal 
to those of white paper. Now, this would scarcely 
be credible, even though under the telescope the 
planet's surface were found to be universally white; 
but, as we find a large proportion of it to be of a 
dull coppery hue, we seem forced to admit that it 
cannot really have an average reflective power nearly 
so great as that calculated by Zdllner. It follows, 
as at least highly probable, that Jupiter shines in 
part by his own light, and this being admitted, we 
cannot but regard it as highly probable that the mass 
of the planet must be intensely hot. 

It may seem, at first sight, that the apparent 
blackness of the satellites' shadows, as seen on the 
disk of Jupiter, is wholly opposed to the view that 
any portion of bis light is native. But, as a matter 
of fact, there is no force at all in this consideration, 
or rather, whatever weight we may attach to the ob- 
served appearance of the satellites ' shadows is in 
favor of the strange theory here put forward. For 
it has been a subject of remark among the most ex- 
perienced observers, that a satellite in transit will 
occasionally appear as dark as its shadow, both seem- 
ing black. The blackness, then, is only apparent, 
and an effect of contrast. In reality, if such ob- 
servations as I have mentioned are to be trusted 
(and I know no reason for disregarding them), the 
shadow of a satellite is not black, and therefore there 



JUPITER, GIANT OF SOLAR SYSTEM 



163 



seems no escape from the conclusion that the surface 
on which they are projected is partially self-luminous. 

A stronger argument against the belief that Ju- 
piter is self-luminous, lies in the fact that the satel- 
lites disappear in his shadow. It must be remem- 
bered, however, that in any case we can assign but 
a small proportion of inherent light to Jupiter, and 
that his satellites would, therefore, in any case, lose 
so large a proportion of their light when passing into 
his shadow, that we might expect them to disappear, 
even under the closest telescopic scrutiny. 

Although I have already far exceeded the limits 
I had proposed to myself for the consideration of 
this noble planet, it is with regret that I take leave 
of him to pass onward to the outermost bounds of 
the solar system. I would fain dwell even longer 
than I have, on a subject of contemplation at once 
so interesting and so instructive. Jupiter, the centre 
of a noble system of worlds, or Jupiter, himself a 
world, inhabited by beings as high perhaps in the 
scale of creation as he himself is in the scheme of 
the planets, is alike a worthy subject of study. The 
more one dwells on the features he presents, the 
more one is impressed with the sense of the grandeur 
of his position in the universe. Surely, whether now 
inhabited or not, he must be intended to be one day 
the abode of noble races. Surely no astronomer 
worthy the name can regard this grand orb as the 
cinder -centred globe of watery matter so contemp- 
tuously dealt with by one who, be it remembered 
thankfully, was not an astronomer. He who has not 






/ 



164 OTHER WORLDS THAN OURS 

gazed hour after hour on the glories of the giant 
planet, gathering fresh delight as feature after feat- 
ure is revealed beneath his scrutiny — he who takes 
his astronomy but at second-hand from the pages of 
the real worker, turning from labors in other fields 
"to see what these star-gazers have to say," may 
lightly disregard the grand lesson which the heavens 
are always teaching, and find only the grotesque and 
the incongruous, where in reality there is the per- 
fectest handiwork of the Creator. But the astron- 
omer, imbued with the sense of beauty and perfec- 
tion which each fresh hour of world -study instils 
more deeply into his soul, reads a nobler lesson in 
the skies. The music which reaches his ears may 
be fitful, but it is not "as sweet bells jangled out of 
tune and harsh"; he may not master its full mean- 
ing, though every note thrills through his inmost 
soul; but, even when its sounds are least distinct, 
they have a beauty and solemnity which are all their 
own. In fine, the true astronomer may say with the 
Pythagorean, but in another sense: 

"There's not one orb which thou behold'st 
But in his motion like an angel sings, 
Still choiring to the young-eyed cherubim; 
But while this muddy vesture of decay 
Doth grossly close us in we cannot hear it," 



CHAPTER VI 

SATURN, THE KINGED WORLD 

IF Jupiter by his commanding proportions affords 
a forceful argument against the view that our 
tiny earth is the only real world in the solar sys- 
tem, Saturn supplies an argument of scarcely inferior 
strength in the singularly complex character of the 
scheme of which he is the centre. No one can con- 
template this glorious planet, as shown by a tele- 
scope of adequate power, without being impressed 
by the conviction that he is looking at a world alto- 
gether more important in the scheme of creation than 
the globe on which he lives. Whether he recognizes 
in the present condition of the planet the result of 
the action of those laws which the Almighty has 
assigned to His universe, or whether he prefers the 
view that Saturn and his system are seen now as 
they were fashioned at the beginning by the Al- 
mighty's creative hand, he is alike amazed at the 
wealth of design exhibited in the scene he is gazing 
upon. He may not be able, indeed, to appreciate 
the true character of the purposes which the various 
parts of the Saturnian system are intended to sub- 

(165) 



166 OTHER WORLDS THAN OURS 

serve, or lie may, in the rash attempt to solve the 
mighty problem, be led to erroneous conceptions; 
but that the great planet is designed for purposes 
of the noblest sort, he cannot gravely question. 1 

In volume and mass Saturn is inferior to Jupiter. 
Jupiter is twelve hundred and thirty times, Saturn is 
not quite seven hundred times, as large as the earth; 
and, while Jupiter outweighs her three hundred times, 
Saturn is scarcely ninety times as heavy as she is. 
Still Saturn is sufficiently large and massive to dwarf 
our earth to insignificance; and even Uranus and 
Neptune, though belonging to the family of the 
major planets, and giants compared with the earth, 
fall below Saturn far more than he does below 
Jupiter. like Jupiter, Saturn rotates very rapidly 
on his axis, the length of his day being about 10J£ 
of our hours. The materials of which Saturn is com* 
posed have a mean density not much greater than 
half that of Jupiter, or less than three-fourths of the 
mean density of water. In fact, Saturn's substance 
is specifically lighter than that of any known planet. 
It seems not impossible that we have in this relation 
some indication of the true cause of that complexity 
of detail which the Saturnian system exhibits. 

The equator of Saturn is inclined about 28£ de- 
grees to the plane in which the planet moves, so that 



1 I know nothing better calculated to lead men to choose astronomy as 
their favorite subject of study than the contemplation of the Saturnian 
system. I can well remember the sensations with which — some eight 
years since — I saw the ringed planet for the first time. I look on that 
view as my introduction to the most fascinating of all the sciences. 



SATURN, THE RINGED WORLD 167 

his seasons (so far as they depend on this circum- 
stance) closely resemble in character those of the 
planet Mars. He occupies about 29% years in cir- 
cling once round the sun — this therefore is the length 
of the Saturnian year. His distance from the sun is 
nearly twice that of Jupiter, and nearly ten times that 
of the earth; so that the amount of light and heat 
which any portion of his surface receives from the 
sun is about ^rst part of that received , by a similar 
portion of the earth's. His orbit being somewhat 
eccentric, however, there is a considerable variation 
in this respect during the course of a Saturnian year, 
insomuch that when he is nearest to the sun he re- 
ceives more light than when in aphelion in the pro- 
portion of about five to four. 

Most of the relations which have to be considered 
in discussing the habitability of Saturn have been 
already dealt with (under very similar conditions) in 
treating of other planets; so that I propose to touch 
on them very lightly, in order to come more quickly 
to those circumstances which distinguish Saturn spe- 
cially among the other members of the solar system. 

Gravity at his equator is almost exactly equal to 
gravity at the earth's surface. Near the poles there 
is a marked increase in the action of Saturnian grav- 
ity, insomuch that a body weighing ten pounds at his 
equator would weigh about twelve pounds at either 
pole. There is nothing, however, in this peculiarity 
which need be specially dwelt upon. 

The length of the Saturnian year, and the small 
quantity of light and heat received from the sun, are 



168 OTHER WORLDS THAN OURS 

simply more marked instances of what has already 
been considered in the case of Jupiter. We may 
conclude with some confidence that these relations 
are quite sufficient to render Saturn wholly uninhab- 
itable by such creatures as exist upon the earth; but 
there seems no reason for supposing that (so far as 
these relations alone are concerned) the planet may 
not be the abode of living beings as high in the scale 
of creation as any which live upon our globe. 

And thus viewing Saturn, we cannot regard even 
the exceptional effects produced by his ring-system 
as of themselves sufficient to banish life from his sur- 
face. These effects are not without interest, however, 
and, as they have been made the subject of some dis- 
cussion, I may be permitted to make a few remarks 
upon them. 

I apprehend that, when Sir John Herschel said 
that the rings occasion an eclipse of nearly fifteen 
years in duration^ first to the northern and then to 
the southern hemisphere of the planet, he meant 
simply that during an interval of such length a large 
portion of either hemisphere was in shadow. He 
knew perfectly well that, long after the edge of the 
ring has been turned directly toward the sun, a very 
large proportion of the hemisphere, over which the 
ring's shadow proceeds to sweep, remains illuminated. 
It had always seemed to me, therefore, altogether a 
mistake on the part of Dr. Lardner to interpret Her- 
schers words as though implying that a whole hemi- 
sphere of the planet is eclipsed for fifteen years in 
succession. 



SATURN, THE RINGED WORLD 169 

So misinterpreting the expression used by Sir 
John Herschel, Dr. Lardner, in his desire to show 
that no such relation existed, was led into real mis- 
takes which a sounder mathematician would not have 
fallen into. He examined the relations presented by 
the ring in a quasi- mathematical, but inexact, manner, 
and came to the following conclusions: "That, by 
the apparent motions of the heavens produced hj the 
diurnal rotation of Saturn, the celestial objects, in- 
cluding the sun and the eight satellites, are not car- 
ried parallel to the edges of the rings; that they are 
moved so as to pass alternately from side to side of 
these edges; that, in general, such objects as pass 
under the rings are only occulted by them for short 
intervals before and after their meridional culmina- 
tion {sic); that, although, under some rare and ex- 
ceptional circumstances and conditions, certain objects 
— the sun being among the number — are occulted from 
rising to setting, the endurance of these phenomena is 
not such as has been supposed, and the places of 
their occurrence are far more limited.' ' All these 
statements are more or less incorrect, and most of 
them are the direct reverse of the truth. The seven 
inner satellites of Saturn stand in an altogether dif- 
ferent relation, with respect to the rings, than all other 
celestial objects, since they travel in the same plane 
and in circles concentric with the outlines of the 
rings: they can, therefore, no more be occulted by 
the rings than an outer ring can be occulted by an 
inner one. So far is it again from being true that 

the sun is in general only occulted for a short time 

Science — 1 — 8 



ITO OTHER WORLDS THAN OURS 

before and after culmination, that the more common 
case (considering the whole planet) is for the sun to 
be eclipsed (if at all) throughout the whole of the 
Saturnian day; and a very common case, left alto- 
gether unnoticed by Dr. Lardner, is, that the sun is 
occulted in the forenoon and afternoon, but free from 
eclipse in the middle of the day. Nor is it true that 
the places where the sun can be totally eclipsed 
throughout the day are limited to a relatively small 
portion of the planet, since every part of the planet 
whence the rings are visible at all has the sun eclipsed 
by the rings throughout the whole day for a longer or 
shorter succession of rotations, and, in the remaining 
or polar regions of the planet, the sun is altogether 
absent for long intervals of time, for the same reason 
that he is absent from the skies of our polar regions 
during a comparatively short interval. As for the 
endurance of the total diurnal eclipses, it is only 
necessary to remark that, in Saturnian latitudes cor- 
responding to that of London or Paris, the sun is 
totally eclipsed for more than five years in succes- 
sion, while in a latitude corresponding to that of 
Madrid he is totally eclipsed for nearly seven years 
in succession. This suffices to show that an arrange- 
ment which the inhabitants of the earth would find 
wholly unendurable prevails over a very large pro- 
portion of Saturn's surface. 1 

1 The views here expressed as to the effects of the Saturnian rings 
are founded on exact mathematical calculation, of which the elements 
are given in my treatise on Saturn. The problem is not by any means 
a difficult one, and the only way in which the erroneous views formed 



SATURN, THE RINGED WORLD 171 

But, if we consider the matter rightly, we shall see 
that this, after all, need not surprise us, since there is 
already in the enormous distance of Saturn from the 
sun the amplest reason for believing that he cannot 
be inhabited by such creatures as exist upon the 
earth. It is in vain that, by conceiving him to be 
surrounded by a dense atmosphere, we assign to him 
a mean climate as warm as that of the earth. The 
want of direct solar heat still remains, and must be 
regarded as a fatal objection to the habitability of 
Saturn by races resembling those with which we are 
familiar. 

In the case of Saturn as in the case of Jupiter, the 
provision of satellites, and of the rings which form so 
glorious an object to the astronomer on earth, is alto- 
gether inadequate to increase the supply of light re- 
ceived by the Saturnians to any such extent as has 
been imagined. Those well-meaning persons who in* 
sist on their own interpretation of the Almighty's 
designs, are singularly successful in overlooking very 
obvious difficulties. If the design of the rings, for 
instance, really were to compensate the Saturnians for 
the small amount of light which they receive from the 
sun, it would surely follow that there was a want of 
wisdom in the selection of an arrangement by which 

by Dr. Lardner can be explained is, by considering that he dealt with 
the problem in a general instead of an exact manner. I could not fed 
any doubt as to the accuracy of my results, but I was not the less 
pleased to receive a letter from Mr. Freeman, a Fellow of St. John's 
College, Cambridge, stating that he had obtained similar results, and 
had constructed a table on the pian of Table XL in my "Saturn," and 
so closely according with it as not to need separate publication. 



172 OTHER WORLDS THAN OURS 

more light is kept away from Saturn than the rings 
can possibly reflect to him. And further, during the 
very season when the extra light derived from the 
rings is most required by the planet, that is, during 
the long nights of the Saturnian winter, they exhibit 
a dark band upon the heavens, concealing whole con- 
stellations from the view of the Saturnian people. As 
far as the satellites are concerned, there is no cor- 
responding difficulty. They undoubtedly reflect the 
sun's light to Saturn, and, if there really are intelli- 
gent beings on the planet, the satellites must undoubt- 
edly present an interesting spectacle, especially when 
a large number of the moons are nearly full. But a 
little consideration will show that, even though all 
the satellites were full at the same time, the quantity 
of light they could send back to their primary would 
be wholly inadequate to compensate for the planet's 
great distance from the sun. According to the best 
estimates of their magnitude, the eight satellites, taken 
in their order from the planet, cover spaces on the 
Saturnian heavens which bear to the space covered 
by our moon the respective proportions of about 2, 
1> li» h |» h Tk, ^y. In all, then, they cover an 
area about six times that of our moon; and as, owing 
to their great distance from the sun, they are illu- 
mined by only T&rth of the light which illuminates our 
moon, they could only send back to the planet, if it 
were possible for them to be all full together, about 
V&th part of the light we receive from the full moon. 
It will be remembered that the light which could be 
reflected from the Jovial moons, if they could be all 



SATURN, THE RINGED WORLD 173 

full together, bears about the same proportion to our 
moon's. We seem forced to the conclusion that the 
satellites were intended to subserve no such design 
as has been imagined. Here, as in many other cases, 
the scheme of the Creator is not so obvious to human 
reasoning as some have complacently supposed. 

But we have now to consider peculiarities which 
suggest that Saturn's globe has not yet reached a 
condition fitting it to be the abode of living creat- 
ures. These peculiarities resemble in great part 
those which have been already noticed in the case 
of Jupiter, but a certain most remarkable phenom- 
enon belongs to the ringed planet alone. 

The belts of Saturn resemble those of Jupiter in 
their general shape and also in their color. The 
dark belts near the equator are of a faint brown or 
ruddy tinge, those near the pole bluish or greenish 
gray, while the bright belts are yellowish — the equa- 
torial belt being the brightest of all and almost 
white. The poles are commonly dusky and even 
sombre in hue. 

The belts change in aspect much as those of Ju- 
piter have been observed to do; and whether we 
regard the change as due to the bodily transference 
of the belts of cloud or to the precipitation of their 
material in the form of rain (while, elsewhere, invis- 
ible vapors are condensed into cloud), we are com- 
pelled to recognize the action of forces altogether 
exceeding those which the sun can be supposed to 
exert upon this distant planet. The light sent to us 
from Saturn also bears a much greater proportion 



174 OTHER WORLDS THAN OURS 

to the amount of solar light actually received by the 
planet than is observed in the case of Mars or the 
moon, and so nearly approaches the proportion no- 
ticed in the case of Jupiter as to lead to the same 
inference — namely, that a portion of Saturn's light is 
emitted from the body of the planet. 

In these respects, and also in the small density 
of the planet, we seem to recognize evidence which 
points to Saturn as probably a heat-sun (if not to 
any very noteworthy extent a light- sun) to the satel- 
lites which circle around him, and not himself the 
abode of living creatures. Without dwelling further 
on evidence already fully considered in the case of 
Jupiter, I turn to one of the most striking facts 
in the whole range of observational astronomy, as 
supplying at once new evidence respecting the con- 
dition of Saturn and strengthening the evidence 
adduced respecting Jupiter. 

If it can be shown that Saturn's globe is subject 
to changes of figure perceptible even across the 
enormous gap which separates him from the earth, 
it will at once be admitted that he can hardly be 
regarded as a globe conveniently habitable. Now, 
I have very little hesitation in saying that evidence 
of the most conclusive kind exists in favor of this 
strange mobility of figure. It will presently be seen 
that it is with the observations of no mere amateur 
astronomers that I have to deal in endeavoring to 
establish as a fact that which has commonly been 
spoken of as an illusion' — the assumption by Saturn 
of his so-called "square -shouldered" figure. 



SATURN, THE RINGED WORLD 



175 



It was in April, 1805, that Sir William Herschel 
first called attention to this peculiarity. The planet, 
which had always presented to him an elliptical 
figure, exhibited a strangely- distorted aspect. A 
well-marked flattening at the equator, accompanied 
by an equally well-marked flattening at the poles, 
gave the planet's globe an oblong figure (with 
rounded angles), the longest diameters having their 
extremities in Saturnian latitude 43° 20' — so exactly 
was the great astronomer able to indicate the nature 
of the deformity, owing to its well-marked character 

What view shall we form respecting an observa 
tion of so remarkable a character? Was the pecu 
liarity due to telescopic distortion? Herschel ob 
served it with several instruments, some seven 
some ten, one twenty, and one forty feet in length 
Was the phenomenon due to atmospheric disturb 
ances? Such disturbances could not account for * 
persistent impression, however well they might ex 
plain the momentary assumption of the square-shoul 
dered aspect by the ringed planet. Besides, Jupiter 
presented no such appearance. Was the appearance 
an optical illusion due to the position of the ring — 
then slightly open? If so, the planet should always 
exhibit the square-shouldered aspect when his rings 
are open to that particular extent; and this is not 
the case. Besides, we ought to notice a similar illu- 
sion, when looking at a picture representing that 
particular phase of Saturn. Must we, then, accept 
the astounding conclusion that the giant bulk of 
Saturn is subject to throes of so tremendous a nature 



176 OTHER WORLDS THAN OURS 

as to upheave whole zones of his surface five or six 
hundred miles above their ordinary level? Truly 
the conclusion is one to be avoided, if we can by 
any possibility find a less startling explanation of 
the matter. 

Yet where are we to look for such an explana- 
tion? Was Sir William Herschel simply deceived? 
I have already considered the general question of 
illusion, but the reader might entertain the explana- 
tion as conceivable that Herschel might for a while 
have lost the acumen which distinguished him — that 
illness, for example, might have rendered his ob- 
servations inexact. But we have abundant evidence 
that the great astronomer was in the full possession 
of all his wonderful powers as an observer during 
the month of April, 1805; we know further that by 
careful measurements he rigidly excluded all pos- 
sibility of illusion affecting his judgment. 

It would be more satisfactory, doubtless, to the 

reader, however, to learn that other observers had 

/ noticed similar peculiarities, or peculiarities which, 

I if not similar, were at least such as to prepare us to 

regard the globe of Saturn as liable to remarkable 
changes of figure. Fortunately, many such observa- 
tions have been recorded. I take the following from 
one of an admirable series of papers on Saturn by 
Mr. Webb, in the "Intellectual Observer" for 1866. 

On August 5, 1803, Schroter found Saturn not 
perfectly spheroidal in figure. Kitchener says that 
for a few months in the autumn of 1818 he saw 
Saturn of the figure described by Sir William Her- 



SATURN, THE RINGED WORLD 111 

schel, and that with two different achromatics. At 
this time the ring must have appeared too narrow to 
account for the appearance as due to illusion. On 
one occasion the Astronomer Eoyal had a similar 
view of Saturn. He remarks, also, that a person 
unacquainted with Herschel's observation remarked 
spontaneously on the flattened equator of the planet. 
On another occasion, Mr. Airy noticed the exact 
reverse, the planet seeming flattened instead of up- 
heaved, in latitude 45°. In January, 1855, Coolidge, 
using the splendid refractor of the Cambridge, U. S., 
Observatory, noticed that the greatest diameter of 
the globe seemed inclined about 20° to the equatorial 
diameter; but on the 9th the equatorial diameter 
seemed the greatest; while on December 6th he says, 
"I cannot persuade myself that it is an optical illu- 
sion which makes the maximum diameter of the ball 
intersect the limb half way between the northern 
edge of the equatorial belt and the inner ellipse of 
the inner bright ring." All this time the rings 
were nearly at their greatest opening, so that any 
illusion should have been of an opposite character 
to that observed when the rings were nearly closed. 
In the report of the Greenwich Observatory for 
1860-61, it is stated that "Saturn has sometimes 
appeared to exhibit the square -shouldered aspect." 
The eminent observers Bond, father and son, have 
noticed similar peculiarities, using the great Merz re- 
fractor already referred to. Each of them noticed 
a flattening of the north-polar regions of the planet 
in the summer of 1848, when the ring was turned 



178 OTHER WORLDS THAN OURS 

edgewise toward us. On the other hand, the same 
observers noticed that in 1855-57, when the ring was 
most widely opened, the polar regions did not always 
seem projected furthest on the outer ring in a sym- 
metrical manner, but four times on the left of the 
pole, once on the right, and once only, exactly oppo- 
site the pole. "The outline of this region also occa- 
sionally appeared irregularly flattened and distorted,' * 
an appearance not satisfactorily explained by the 
juxtaposition of the dark shadow of the planet on 
the ring. 

Now, there can be no doubt whatever that the 
planet Saturn is not ordinarily distorted. In 1832, 
during the disappearance of the ring, Bessel carefully 
determined the figure of the planet's disk, and Main 
in 1848 (when the ring was again turned edgewise 
toward us) made similar measurements. Each of 
these trustworthy authorities came to the conclusion 
that the disk of Saturn did not, at the seasons when 
they respectively measured it, exhibit any distortion 
of figure such as Herschel had described. 

We seem almost compelled, therefore, to accept 
the conclusion that the planet Saturn is subject to 
the influence of forces which either upheave por- 
tions of its surface from time to time, or cause vast 
masses of cloud to rise to an enormous height above 
the mean layer of Saturn's cloud-envelope. Which- 
ever view we adopt, we cannot fail to recognize the 
fact that an intense heat must in all probability pre- 
vail in the great globe of Saturn; and doubtless the 
real mass of the planet must emit a brilliant light, 



SATURN, THE RINGED WORLD 179 

though, the cloud-strata surrounding him may pre- 
vent us from recognizing more than a minute propor- 
tion of his luminosity. In fact, according to this 
view, Saturn and Jupiter, unlike the sun, whose real 
substance emits a less intense light than the cloud - 
photosphere surrounding him, must have nuclei — 
solid or liquid — shining with an altogether more bril- 
liant light than the cloud-envelopes of these planets 
seem actually to emit. 

Why Saturn, rather than Jupiter, should exhibit 
these mysterious changes of figure, is readily expli- 
cable when we remember the near coincidence of the 
planes in which the Jovial satellites move with the 
orbital plane of their primary. There thus always 
results a close agreement between the zone on which 
the satellites exert their greatest disturbing influ- 
ences, and that most influenced by the solar action. 
No such coincidence exists in the case of Saturn, 
whose satellites travel in a plane inclined nearly 
thirty degrees to that in which their primary trav- 
els. It is worthy of mention, however, that Schro- 
ter, an accurate and practiced observer, records that 
on certain occasions he thought he could detect par- 
tial flattenings of the disk of Jupiter (see also 
Preface). 

I think the evidence in the case of Saturn favors, 
at least as strongly as that which has been adduced 
in the case of Jupiter, the belief that the giant planets 
outside the zone of asteroids are not themselves suit- 
able abodes for living creatures, but are suns, supple- 
menting the small amount of light, and yet more fully 



180 OTHER WORLDS THAN OURS 

supplementing the small amount of heat, which the sun 
supplies to the satellites which circle around these 
orbs. Undoubtedly, if we are to judge according to 
the method which has been so often applied to such 
questions, if we are to ask ourselves according to 
what arrangement the central planets and the schemes 
circling around them seem most reasonably interpreted, 
we should at once adopt some such conclusion. For, 
by taking Jupiter and Saturn to be strictly analogous 
to our own earth, and their satellites to be subsidiary 
bodies, resembling our moon in this, that they sub- 
serve at present no other purpose but to illuminate 
the nocturnal skies and to sway the oceans of their 
primaries, we find ourselves perplexed by the consid- 
eration that a much simpler arrangement would have 
subserved these purposes much more completely. In 
the case of Saturn's satellites, indeed, it seems diffi- 
cult to conceive that these bodies could have been 
intended to fulfil any such purposes, since the two 
outer ones could neither give any useful light to their 
primary, nor sway appreciably any oceans which may 
exist upon the planet. 

On the other hand, if Saturn and Jupiter are suns 
to their satellites, we see in the Saturnian and Jovial 
systems real miniatures of the solar system. We no 
longer require that the planets themselves should be 
habitable, any more than we require that our sun 
should be so. In fine, we do not find in any por- 
tion of either system that waste of material which per- 
plexes us under the former arrangement. 

I do not say that this mode of reasoning has any 



SATURN, THE RINGED WORLD 181 

great force. On the contrary, I am disposed to 
demur to the opinion that it is given tc man to as- 
sign a reason for all things which science may reveal 
to him. For reasons which seem to me far more con- 
vincing, I am led, however, to believe that the two 
most important members of the planetary scheme 
must be left without inhabitants for the present, 
while in exchange I submit to the contemplation of 
the curious twelve small orbs, constituting two mini- 
ature world-systems. The condition of these worlds 
will be touched on briefly in a separate chapter. 



CHAPTEK VII 

URANUS AND NEPTUNE, THE ARCTIC PLANETS 

A CIRCUMSTANCE which is of great importance 
in considering the relations of the outer plan- 
ets is apt to be lost sight of, owing to the un- 
satisfactory manner in which, in nearly all books on 
astronomy, the planetary orbits are represented. To 
look at the series of equi-distant and concentric cir- 
cles representing the orbits of the planets, who would 
suppose that, in passing from the orbit of Jupiter to 
that of Saturn, a distance &ye times as great as that 
which separates our earth from the sun has to be 
traversed? But the distance separating Uranus from 
Saturn is twice as great even as this tremendous gap, 
while Neptune travels as far beyond Uranus as 
Uranus beyond Saturn. Nine hundred millions of 
miles in width is the enormous gap by which the path 
of Uranus is separated from that of the ringed planet 
on the inner side, and from that of distant Neptune 
on the outer, so that a line equal to the diameter of 
Jupiter's orbit would barely suffice to reach from 
Saturn to Uranus, or from Uranus to Neptune, even 
when either pair of planets are in conjunction. 
(182) 



URANUS AND NEPTUNE, ARCTIC PLANETS 183 

We know so little of the physical aspect of Uranus 
and Neptune that it is extremely difficult to form any 
opinion as to their condition. The two planets re- 
semble each other in size, each being far smaller than 
either of the giant orbs we have lately been consider- 
ing. Uranus has a diameter of about 33.250 miles; 
Neptune is somewhat larger, his diameter having 
been estimated at 37,250 miles. The volume of 
Uranus is 74, the volume of Neptune 105, times 
that of the earth. Both planets exceed Saturn in 
density; for, whereas Saturn's mean specific gravity 
is but t\feths, that of Uranus is rifcths, and that of 
Neptune ltoths, of the mean specific gravity of our 
globe. Thus each planet has a density nearly equal 
to that of water. The mass of Uranus exceeds the 
earth's about 12% times, while that of Neptune is 
some 16f times as great as the earth's. It will be 
seen, therefore, that though these two far-distant 
worlds are much less massive than Jupiter or Saturn, 
each of them outweighs many times the combined 
mass of the four planets which travel within the 
zone of asteroids. Yet gravity on the surface of 
these two orbs is but about three-fourths of terres- 
trial gravity. 

The disk of the sun as seen from Uranus is less 
that that which we see in the proportion of nearly 
390 to 1, while the Neptunians have a sun only about 
sfoth of ours, in apparent size; and in these propor- 
tions the solar light and heat received by these plan- 
ets are respectively diminished. So small does the 
sun appear, in fact, that to eyes such as ours his 



184 OTHER WORLDS THAN OURS 

orb could not present a disk-like figure, but would 
appear like an exceedingly brilliant day-star. 

So far we have found the circumstances of the two 
planets somewhat similar. But we have now to con- 
sider a relation presented by Uranus, which is not 
shared in by Neptune. It may be remarked that we 
know so little about either planet that any very care- 
ful consideration of their habitability would be simply 
a waste of labor. The evidence I am about to ad- 
duce, however, in the case of Uranus, seems thor- 
oughly to dispose of the claim of this planet to be 
regarded as a world inhabited by creatures resembling 
those we are acquainted with on earth; and, as we 
cannot reasonably suppose Neptune to be inhabited 
by such creatures while Uranus is not, we may very 
fairly regard the question as disposed of for both 
planets, even though the relation dealt with is pe- 
culiar to Uranus. 

We know that in the case of Jupiter, as in that of 
Saturn, the position of the plane near which the satel- 
lites travel is nearly coincident with the plane of the 
primary's equator. Therefore, though no telescope 
has yet exhibited any features on the disk of Uranus 
which can enable us to determine the position of its 
equator, we can reasonably infer from the motion of 
the satellites how the equator of the planet is sit- 
uated. 

Now, the satellites of Uranus travel in a plane 
very nearly at right angles to the plane in which the 
planet travels. It may be mentioned also, though not 
important for my present purpose, that they travel in 



UBANUS AND NEPTUNE, ARCTIC PLANETS 185 

a retrograde direction. We conclude, then, that the 
axis of Uranus lies very nearly in the plane wherein 
the planet moves around the sun, and that the planet 
rotates in such a way around this axis that the sun 
moves across the Uranian skies from west to east, 
instead of from east to west. The latter relation is 
of no great importance; the former, however, in- 
volves results which dispose at once, and thoroughly, 
of any hopes we might entertain of discovering creat- 
ures in Uranus resembling those which inhabit the 
earth. 

The inclination of the plane of Uranus's equator 
to the path in which he travels being about 76 de- 
grees, it follows that the Uranian sun has a range 
of about 76 degrees on either side of the celestial 
equator, during the long Uranian year. Already, in 
considering the seasons of Venus, I have dealt with a 
peculiarity of this sort; but in the case of Uranus the 
effects are more serious. We have only to consider 
what would be the result of so wide a r inge of solar 
excursion north and south of the celestial equator in 
a latiimde corresponding to that of London, to see how 
importantly the climatic relations of a planet like 
Uranus, occupying eighty-four years in circling once 
around the sun, must be affected by such a peculi- 
arity. We know that in the latitude of London the 
sun reaches at noon, in spring or autumn, an eleva- 
tion of about 88% degrees above the southern hori- 
zon, that in summer he passes the meridian 23J£ 
degrees higher, while in winter he passes the me- 
ridian 23J^ degrees lower, or only fifteen degrees 



186 OTHER WORLDS THAN OURS 

above the horizon. But in a similar Uranian lati- 
tude, while the sun would reach the same meridian 
elevation in spring or autumn, he would in summer 
travel throughout the day in a small circle, fourteen 
degrees only from the pole (raised of course 51% de- 
grees above the northern horizon). And obviously, 
since the year of the Uranians lasts eighty-four of 
our years, the continuance of the sun above the hori- 
zon would last for many years. 1 So far there is 
nothing to render life in Uranus unpleasant, always 
supposing the small amount of light and heat sup- 
plied by the sun to be compensated by some such 
atmospheric arrangements as physicists have thought 
necessary for the convenience of the more distant 
planets. But, when we consider the nature of the 
Uranian winter, we find the circumstances such as no 
such arrangements can be conceived to alleviate. The 
winter path of the Uranian sun, in a latitude corre- 
sponding to that of London, is just as fully pressed 
below the horizon as the summer path is raised above 
it. At midnight the sun is 65% degrees, at nominal 
noon he is 37% degrees, below the southern horizon. 
And as with the summer day, so with the winter 
night, years elapse before either comes to an end. 
For upward of twenty years, in a latitude corre- 



1 Exact calculation applied to relations so uncertain as those here in 
question would be out of place. From a careful construction, however, 
with 16° as the assumed value of the inclination of the equator of 
Uranus to the plane of his orbit, I find that the sun would continue 
above his horizon in summer for about 23£ years. Of course, it fol- 
lows that the sun would continue below the horizon for an equally long 
period in winter! 



URANUS AND NEPTUNE, ARCTIC PLANETS 187 

sponding to that of London, the Uranians — if there 
are any — never see the small Uranian sun. During 
all this long time, too, a sight even is denied them 
of all parts of the solar system, interior to the orbit 
of Uranus; though this deprivation cannot be re- 
garded as very serious when it is remembered that to 
such eyesight as ours Saturn could barely be visible 
from Uranus, even when most favorably situated, 1 
while Jupiter, always near the sun, could only be 
occasionally seen, shining with a light somewhat less 
than a fiftieth of that which he reflects to us when in 
opposition. 

When we consider other latitudes, we still find 
Uranus ill provided for as respects his winter season. 
In all latitudes nearer the pole than the latitude just 
considered, the Uranians have winters lasting from 
twenty years to upward of forty. In latitudes nearer 
tl 3 equator the winter night is shorter, but we must 
approach quite close to the equator before we reach 
a latitude where the winter night lasts less than a 
year or so. Over a belt extending about fourteen 
degrees on each side of the equator there is a peren- 
nial succession of days and nights never exceeding 
tne full duration of the Uranian diurnal rotation. 



1 Admiral Smyth, speaks of Saturn as a fine morning and evening 
star for the Uranians; but, though Saturn may be visible, he can 
hardly be a fine object. At his elongations he is twice as far from 
the Uranians as he is from us when in opposition, and further he pre- 
sents but a half disk. His light must in fact be reduced to less than 
one- eighth of that which he presents to us when in opposition; and, 
as, instead of being on a black sky, he must be always seen from 
Uranus on a twilight sky, he cannot appear a very fine object. 



188 OTHER WORLDS THAN OURS 

But we must not suppose that we have thus found 
an Elysian zone in Uranus. The immense range of 
the sun's excursions produces here also a variety 
of seasonal changes which we should find altogether 
unendurable. From a sun barely rising above the 
horizon in winter, to a sun which rises vertically 
overhead twice in the course of the Uranian summer, 
is a change which hardly accords with our views of 
what is desirable in the progress of the seasons. At 
the equator itself there are in reality two summers, 
occurring at the period of the sun's passing the celes- 
tial equator. Here for many years together the sun 
passes day after day to a point nearly overhead. 
But then comes the long winter, in the heart of 
which the sun rises barely fourteen degrees above 
the northern or southern horizon. By whatever 
arrangement we render the long Uranian winters in 
this part of the planet endurable, we render the heat 
of his long summers unendurable; and vice versa, 
if we conceive of atmospheric relations which would 
render his summers pleasing, we have caused his 
winters to be so intensely cold that no creatures we 
are familiar with could endure the prolonged and 
bitter frosts, contrasting so distressingly with the 
imagined geniality of his summer weather. 

If Uranus be inhabited at all, then, it must be 
by creatures constituted in a very different manner 
from any with which we are acquainted. To such 
creatures, if any among them be gifted with intelli- 
gence, the heavens, though not adorned with planets, 
must yet present an interesting subject of study. 



URANUS AND NEPTUNE, ARCTIC PLANETS 189 

The position of the pole, lying close by the zodiac, 
so that among the zodiacal constellations there must 
be all the varieties of motion which we recognize 
in passing from the equatorial to polar constellations, 
would lead to a certain complexity in celestial charts 
and globes, which would invite us to the conclusion 
that the Uranians must be capital mathematicians. 
Then there are certain astronomical subjects of study 
to which their mathematical powers may be devoted 
perhaps more successfully than those of our astron- 
omers. For example, the wide sweep of the planet's 
orbit would enable the Uranians to recognize a dis- 
placement of the stars in the course of the long 
Uranian year. The star Alpha Centauri, which only 
exhibits to the terrestrial observer an annual parallax 
of one second, would exhibit to the observer in 
Uranus a displacement of about the third part of a 
minute. Other stars would be affected in like pro- 
portion, and perhaps the Uranians may thus be 
enabled to form some conception of that relation 
which hitherto has proved too baffling a problem 
to our astronomers — the actual configuration of the 
nearer parts of the sidereal system. The Neptunians 
would of course be even more favorably circum- 
stanced. 

One difficulty presents itself, however, in thus 
considering the prospects of the Uranian and Nep- 
tunian astronomers. The enormous length of the 
year of each planet requires that either the astron- 
omers in Uranus and Neptune should be very long- 
lived, or that they should be very enthusiastic in 



190 OTHER WORLDS THAN OURS 

the cause of science, to prosecute singly such ob- 
servations as Henderson, Olbers, or Peters, have 
singly prosecuted on our earth. A Uranian who 
made one set of observations to determine stellar 
parallax when he was, say, twenty-five years old, 
would have to wait till he had nearly reached the 
threescore years and ten (not perhaps allotted as 
the span of Uranian life) before he could make the 
corresponding set, by comparing which with the 
former, stellar parallax was to be determined. In 
Neptune, life must be prolonged over the century 
(unless the study of observational astronomy com- 
mence during the babyhood of the Neptunians) in 
order that a complete set of observations for deter- 
mining stellar parallax should be carried out. One 
cannot but conceive that a certain sluggishness must 
mark the progress of astronomy in these far-off 
worlds under such circumstances. In fact, the mere 
consideration that, after a constellation has passed 
away from the nocturnal skies of Uranus or Nep- 
tune, thirty or forty years in one case, and seventy 
or eighty in the other, must pass before the con- 
stellation again becomes favorably visible, suggests 
characteristics of astronomical observation altogether 
different from those we are familiar with. 

Admiral Smyth suggests that these distant planets 
must be convenient outposts for watching the ap- 
proach or recession of comets; but, with all diffi- 
dence, I would venture to point out that the inhabi- 
tants of the earth are, on the whole, more favorably 
situated in this respect. Every large comet which 



URANUS AND NEPTUNE, ARCTIC PLANETS 191 

approaches tolerably near to the sun during peri- 
helion passage is as likely to be seen as to be missed 
by the inhabitants of earth; but scarcely one out of 
a thousand such comets would be seen from Uranus 
or Neptune, since, to be visible, a comet must ap- 
proach the sun or recede from him along a course 
passing tolerably near to the particular position of 
either planet at the time; and the chances in the 
case of any individual comet would be enormously 
against such a contingency. 

With eyesight such as ours, the Uranians could 
distinctly see Neptune when in opposition, but the 
Neptunians would be wholly unable to see Uranus, 
or indeed any known planet of the solar system. 

Perhaps, though we have very little evidence on 
the point, it will be thought more reasonable to sup- 
pose that Uranus and Neptune are suns to their 
respective systems of satellites, than to imagine that 
these two drearily-circumstanced planets are them- 
selves inhabited. Their satellites cannot possibly 
compensate, to any noteworthy extent, for the small 
amount of solar light or heat which reaches their 
primaries. On the other hand, it is not difficult to 
conceive that the planets may afford an important 
supply of heat (at any rate) to their dependent orbs. 
Certainly, so far as the evidence we have extends, 
Uranus and Neptune resemble Saturn and Jupiter 
too closely not to warrant the application of any 
arguments deduced from the appearance of the two 
giant planets to the case of their inferior but still 
gigantic brethren. 



192 OTHER WORLDS THAN OURS 

Viewing the matter thus, we seem led to the con- 
clusion that the planets which lie outside the zone 
of asteroids are distinguished from those within that 
belt, not merely, as had so long been recognized, 
in the attributes of size, density, rapidity of rotation, 
and complexity of the systems circling around them, 
but in this more important and more interesting cir- 
cumstance, that they and their dependent orbs are 
real miniatures of the solar system. Four suns they 
would seem to be, not indeed suns resplendent like 
the primary sun around which they travel, but still 
giving out perhaps no insignificant supply of light; 
not heated to incandescence as he is, but still supply- 
ing an amount of heat proportionately far greater 
than the quantity of light they give forth: in fine, 
not, as he is to the inner planets, the sole source 
whence all supplies of force are derived, but adding 
their influence to his in a variety of complicated but 
doubtless well-ordered combinations, in such sort 
that the small worlds which circle around them are 
provided with all that is needful to the well-being of 
their inhabitants. 



CHAPTER VIII 

THE MOON AND OTHER SATELLITES 

ALTHOUGH I do not think that the moon can 
be regarded as probably at present the abode 
of life, there are many reasons for studying in 
a work on other worlds the various relations she 
presents to us. In the first place, she subserves 
various useful purposes in the 3conomy of oar own 
earth; then there are circumstances in her appear- 
ance which suggest that at one time there may have 
been life upon her surface; and, lastly, she affords 
us the only information we have concerning the 
probable relations presented by the noble systems of 
moons which circle around Jupiter and the other 
planets outside the orbit of the asteroids. 

Now, with regard to the present habitability of 
the moon, it may be remarked that we are not justi- 
fied in asserting positively that no life exists upon 
her surface. Life has been found under conditions 
so strange — we have been so often mistaken in as- 
suming that here certainly, or there, no living creat- 
ures can possibly exist — that it would be rash indeed 
to dogmatize respecting the state of the moon in 
this respect 

SCIENCE— 1— 9 (193) 



194 OTHER WORLDS THAN OURS 

Still, in the case of the moon we have relations 
wholly different in character from those we have 
hitherto had to consider. We no longer have to deal 
with a question of the various degrees of heat and 
cold, of atmospheric rarity or density, and the like, 
but with relations which do not in the slightest de- 
gree resemble those we are familiar with on earth. 

In the first place, the moon has no appreciable 
atmosphere. We have long known this quite cer- 
tainly, because we see that when stars are occulted 
by the moon they disappear instantaneously, whereas 
we know this would not be the case had the moon 
an atmosphere of appreciable extent. But if any 
doubt could have remained, the evidence of the spec- 
troscope in Mr. Huggins's hands would have sufficed 
to remove it. He has never been able to detect a 
sign of the existence of any lunar atmosphere, 
though Mars and Jupiter, so much further from us, 
have afforded distinct evidence respecting the at- 
mospheres which surround their surface. 

Then, secondly, there are no seas or oceans on 
the moon. Were there any large tracts of water $ the 
tremendous heat to which the moon is subjected 
during the course of the long lunar day (lasting a 
fortnight of our time) would certainly cause enor- 
mous quantities of water to evaporate; and not only 
would the effects of this process be distinctly recog- 
nizable by our telescopists, but the spectroscope 
would exhibit in an unmistakable manner the pres- 
ence of the aqueous vapor thus formed. 

Thirdly, there are no lunar seasons. The inclina- 



THE MOON AND OTHER SATELLITES 195 

Hon of the moon's axis to the orbit in which she 
travels around the sun is nearly 89°, and with this 
inclination there can be no appreciable seasonal 
changes. 

Fourthly, the enormous length of the lunar day 
is altogether opposed to our conceptions of what is 
suitable for animal or vegetable life. The lunar 
day lasts about a fortnight, and the lunar night is, 
of course, equally long. Were this all, the incon- 
venience of the arrangement would be unbearable 
by beings like ourselves. But far more serious con- 
sequences must result from the combination of the 
arrangement with the want of an atmosphere; for 
whereas during the lunar day the surface of the 
moon is exposed to an inconceivably intense direct 
heat, undoubtedly sufficient to heat that surface far 
above the boiling-point, during the lunar night the 
heat is radiated rapidly away into space (no atmos- 
phere checking the process), and an intensity of cold 
must prevail of which we can form but imperfect 
conceptions.* 



1 The moon's physical habitudes are in fact so very different from those 
of the earth that one cannot read without astonishment the well-known 
passage in which Sir W. Herschel pleads for the moon's habitability. "Its 
situation, with respect to the sun," he says, "is much like that of the 
earth, and by a rotation on its axis it enjoys an agreeable variety of sea- 
sons ( !) and of day and night. To the moon, our globe will appear to be 
a very capital satellite, undergoing the same regular changes of illumina- 
tion as the moon does to the earth. The sun, the planets, and the starry 
constellations of the heavens, will rise and set there as they do here, and 
heavy bodies will fall on the moon as they do on the earth. There seems 
only to be wanting, in order to complete the analogy, that it should be 
inhabited like the earth." The evidence is, however, all the other way. 



196 OTHER WORLDS THAN OURS 

The mere fact that our earth is always invisible 
to three-sevenths of the moon's surface is one which 
points very strongly to the conclusion that the pres- 
ent condition of the moon is not the one best calcu- 
lated to meet the wants of living creatures on her 
surface. In long-past ages, when her rotation had 
not yet been forced into accordance with her revo- 
lution 1 (as at present), the earth must have subserved 
a variety of most important purposes. If water then 
existed on the surface of the moon, the earth must 
have raised tidal waves in her oceans. She must 
further have reflected enormous supplies of light and 
heat toward her dependent orb, even if at that time 
she were not a secondary sun for the lunarians. She 
must have travelled across the lunar skies as the 
moon travels over ours, presenting a variety of in- 
teresting and beautiful phases affording useful time- 
measures, and so enabling the travellers on the moon 
in those long-past ages to guide their course in safety 
over her oceans or her deserts. But now she is in- 



1 The researches of Adams into the peculiarity of the moon's mo- 
tion, called her acceleration, suffice to show that, under the influence 
of the moon's attraction on our oceans, the earth's rotation is gradually 
diminishing ; so that, though many millions of ages must elapse first, she 
will one day so rotate as to keep always the same face turned toward 
her satellite. We cannot doubt that it has been by a process of this 
sort that the moon's rotation has been brought to its present rate. In 
fact, independently of the evidence afforded by the earth's gradual loss 
of rotation, we cannot account for the moon's peculiarity of rotation 
without regarding it as due to the earth's controlling influence. A per- 
fectly homogeneous sphere, started on a direct line at the moon's dis- 
tance, and with the same velocity, would travel without rotation on *n 
orbit like the moon's, and would thus, in completing a revolution, ex- 
hibit every part of its surface to us. 



THE MOON AND OTHER SATELLITES 197 

visible from a large portion of the moon's surface, 
and almost a fixture in the skies of those parts, even, 
of the moon whence she can be seen. Were there 
lunar oceans, she could raise no tides in them. Were 
there a lunar atmosphere, she could shed no heat, to 
be garnered up, so to speak, by that atmosphere, and 
to compensate, in some sort, for the long absence of 
the sun. 

But have we evidence that at some far-distant 
epoch the moon was inhabited? Taking for our guid- 
ance the analogies which are available to us, can we 
really conclude that once, in all probability, those 
barren wastes were clothed with vegetation, those 
dreary solitudes the abode of life? 

When we contemplate with attention the lunar 
surface, considering the indications it presents of 
past activities, we are led to inquire how the forces 
which have been so busily at work were expended. 
If Nature, studied thoughtfully, teaches us the lesson 
that there is no form of force which is not the repre- 
sentative of some other preacting form of force, she 
also teaches us that no form of force ever works 
without generating other forces as its own energies 
are expended. The meteor which sweeps with plan- 
etary velocity through space may be brought to rest 
upon the sun, but the energy stored up in its motions 
is not wasted ; the sun may expend the stores of force 
he derives from meteoric impact, but not idly; 1 all 



1 The question may be asked, "What becomes of the immense sup- 
plies of light and heat continually poured by the sun and other stars 
into space? We cannot tell; yet we know certainly that they cannot 



198 OTHER WORLDS THAN OURS 

round us we see the fruits of solar energies, we feel 
them within ourselves, we exert them upon others. 
And, therefore, when we see on the moon signs that 
her surface was at one time upheaved by tremendous 
volcanic forces, we are led to the conclusion that be- 
tween the era when she was thus disturbed, and the 
present time, when she seems absolutely quiescent, 
there must have been a period when her energies were 
employed in sustaining various forms of life. There 
has, in this instance, been a process resembling ex- 
haustion, though we know the forms of force which 
have passed away from the moon have not really 
ceased to exist; but before the lunar forces were dis- 
sipated into space, so to speak, they must have sub- 
served that great purpose which seems the end of all 
Nature's workings — the support of life. 

Associated, however, with this subject, there are 
questions of a perplexing character, which invite our 



be wasted. The heat of Arcturus, measured by Mr. Stone, gives an 
account of one large portion of the stellar heat-supplies, because we 
know that, small as the amount we receive may be, we must multiply 
that amount millions on millions of times to get the total received by all 
the orbs in space from this particular sun. But we know that a large 
portion of our sun's light and heat must either fail to fall on any other 
orbs, or must be gradually exhausted in its progress through space (for, 
if lines from the sun in every direction encountered orbs, the sky ought 
to be lighted up at all times with star-splendor — which is no other than 
sun-splendor). In either case we cannot tell what becomes of the por- 
tion seemingly wasted, though in the latter case we may affirm confi- 
dently that there is simply a change in the nature of the force. In 
both cases we know that the total of force in the universe remains un- 
diminished. There is, indeed, a seeming contradiction here; but it is 
not different in character from the seeming contradictions suggested by 
the consideration of infinite space and infinite time, which yet we are 
compelled to recognize as absolutely as finite space or finite time. 



THE MOON AND OTHER SATELLITES 199 

careful consideration. If life ever existed on the 
moon, that orb must have possessed an atmosphere 
and seas. Independently, also, of our views on the 
subject of life upon the moon, we are led, by the rev- 
elations of the spectroscope respecting the solar sys- 
tem, to believe that all the bodies within that system 
are in a general sense similarly constituted; and, if 
this be so, there must once have been oceans and air 
upon the moon. What has become of the moon's at- 
mospheric envelope, and of the lunar oceans? 

In four several ways this question has been an- 
swered. Some have thought that the oceans and air 
have been withdrawn into cavities within the moon's 
substance. Others have imagined that the air and 
oceans may have passed away to the further hemi- 
sphere of the moon. According to a third theory, a 
comet has carried off the lunar oceans and atmos- 
phere. And, lastly, a fourth theory has been main- 
tained, according to which the lunar air, and a 
fortiori the lunar seas, have beeen changed by in- 
tensity of cold into the solid form. 

Of these theories, the first and last only seem 
worthy of consideration. We see so much of the 
moon's further hemisphere during her librations that 
we must perforce reject the second, even if we had 
any trustworthy analogy for believing so strange an 
arrangement to be possible. 1 The third theory is op- 

1 Professor Newcombe, of America, has shown excellent reasons for 
doubting whether even that displacement of the moon's gravity, on 
which the theory has been based, can be admitted as an established 
fact. Independently of this, however, the theory will not bear exam- 
ination. Any one who will draw a cross-section of the moon (in a 



200 OTHER WORLDS THAN OURS 

posed by all that modern astronomy teaches respect- 
ing the constitution of comets. 

The theory that an atmosphere formerly surround- 
ing the moon has passed with the lunar oceans into 
the interior of our satellite has been supported by 
physicists of considerable eminence. The relatively 
low specific gravity of the moon (little more than half 
the earth's) suggests the possibility that cavities large 
enough to contain even all the waters of our own 
oceans may exist within the moon. Nor does the 
fact that we can see no unmistakable signs of chasms 
extending deep into the moon's substance suffice to 
render the theory untenable, or even improbable. It 
is difficult to understand how the inrush of the waters 
took place. Certainly it cannot have happened while 
the moon's volcanic forces were in vigorous action; 
yet a period must undoubtedly have arrived when 
by little and little the waters could retire within the 
moon's substance without being vaporized. From 
what we know of volcanic action on the earth, the 
lunar volcanoes must have drawn fresh supplies of 
energy from the gradual influx of water; and one 
can thus understand why the aspect of the moon in- 
dicates that, up to the last moment, so to speak, of 
her existence as a world, the forces upheaving her 
crust were busily at work. We can thus see how it 
has come to pass that the moon's surface shows so 
few signs of the action of rain or running water. 

plane passing through the earth), and endeavor to assign such a posi- 
tion to an atmosphere of moderate extent that, even during the moon's 
extreme librations, no signs of the atmosphere could be perceptible from 
the earth, will at once see that the theory is untenable. 



.J\ 



THE MOON AND OTHER SATELLITES 201 

The theory that the lunar oceans have become 
frozen, and that afterward even the gases forming 
the lunar atmosphere have become solidified, was 
maintained bj Buffon and Bailly in the last cent- 
ury, and has been supported by several astronomers 
in our own day. In some respects, the aspect of 
the moon (especially the absence of well-marked 
colors from her surface) seems to favor the theory. 
Nor need the excessive heat to which the moon's 
surface is exposed for weeks at a time be consid- 
ered a sufficient reason for rejecting it, because we 
have no means of judging how that heat would act 
where there is no atmosphere to prevent its imme- 
diate and entire reflection into space. We know 
that, despite the intense heat which is poured upon 
the summits of the Himalayas, the snow there — 
though a portion may melt during the day — remains 
year after year and age after age undiminished; and 
en the summit of the Himalayas the atmosphere is 
dense and heavy compared with that which exists 
even in the lowest abysms of the lunar ravines. If 
absolute reliance be placed on the results which have 
been deduced from the application of the great Par- 
sonstown mirror to the measurement of the lunar 
heat, it would seem as though we must abandon the 
belief in the existence of frozen oxygen or nitrogen on 
the moon's surface, since, according to those results, 
a large proportion of the moon's heat is radiant — in 
other words, the moon's surface has been actually 
raised to a high degree of heat by the solar rays. At 
present, however, physicists are not prepared to look 



\ 



202 OTHER WORLDS THAN OURS 

with perfect confidence on the method by which, in 
the researches made at Parsonstown, an attempt has 
been made to distinguish between the heat which the 
moon reflects and that which she radiates into space. 

On the whole, however, the former theory seems 
to have the strongest evidence in its favor, or rather 
the least decisive evidence against it. 

In considering the systems of bodies which circle 
around the outer planets, we are struck at once by 
several marked circumstances of contrast between their 
condition and that of our own moon. 

In the first place, we have no satisfactory evidence 
that the satellites of Jupiter and Saturn turn always 
the same face toward their primary. It is true that 
Sir William Herschel was led by certain observations 
of the satellites of Jupiter to conclude that this rela- 
tion holds in their case. But we have far stronger 
evidence against such a view, in the fact that modern 
observers, armed with telescopes of the most exquisite 
defining powers, have not only been unable to con- 
firm the relatively rough observations made by Her- 
schel, but have noticed peculiarities of appearance 
only explicable by the theory that the rotation of 
the satellites is quite independent of their motion of 
revolution around Jupiter. Dawes, for instance, has 
observed that the markings seen on the third satellite, 
when transiting Jupiter's disk, are variable. Bond 
has seen this satellite as a well-defined black spot on 
certain occasions, while on others it has appeared 
quite bright on the disk of the planet. He once saw 
this satellite bright as it entered on the disk of Jupi- 



V 



THE MOON AND OTHER SATELLITES 203 

ter, and about half an hour later as a dark spot; while 
Mr. Prince, with a powerful reflector, has seen the 
satellite dark first and afterward bright. It need 
hardly be said that, if the satellite turned always the 
same face toward its primary, no such varieties of ap- 
pearance would be presented during transit. The fol- 
lowing passage from Webb's " Celestial Objects" points 
strongly also to the conclusion that the rotation of the 
Jovial satellites must be independent of their revolu- 
tion. After mentioning that the variable light of the 
satellites may be caused by the existence of spots 
upon their surface, he proceeds: "A stranger source 
of anomaly has been perceived — the disks themselves 
do not always appear of the same size or form. Ma- 
raldi noticed the former fact in 1707, Hersehel ninety 
years afterward inferring also the latter, and both 
have since been confirmed. Beer and Madler, Las- 
sell and Secchi, have sometimes seen the disk of the 
second satellite larger than that of the first; and Las- 
sell, and Secchi and his assistant, have distinctly seen 
that of the third satellite irregular and elliptical; 
while, according to the Eoman observers, the ellipse 
does not always lie the same way." 

It will easily be seen that these peculiarities indi- 
cate the existence of dark markings on these bodies, 
and that, as the satellites rotate, the varying posi- 
tion of these markings causes the satellites seem- 
ingly to change in figure, since the brighter part of 
the satellite would be that which would determine 
its apparent figure. And further, since the change 
of figure shows no correspondence with the position 



204 OTHER WORLDS THAN OURS 

of the satellites in their revolution, we infer that 
their revolution is independent of their rotation. 

It is worthy of notice, however, that even if the 
inner satellites turned always the same face toward 
their primary, the peculiarity would not (as in the 
case of our moon) result in an inordinate lengthening 
of their diurnal period, since Jupiter's two inner 
satellites complete a revolution in one day eighteen 
and a half hours, and three days thirteen hours re- 
spectively; while the revolutions of Saturn's five 
inner satellites are severally accomplished in twenty- 
two and a half hours, one day nine hours, one day 
twenty-one hours, two days eighteen hours, and four 
days twelve and a half hours. 

So far as we can judge from Laplace's estimates, 
the specific gravity of Jupiter's moons must be very 
small indeed, ranging from one-ninth to four-fifths 
of the specific gravity of water. But very little reli- 
ance can be placed on these results, because the only 
evidence we have respecting the mass of the satellites 
is that founded on the perturbations to which their 
motions are subjected, and it is very difficult indeed 
to estimate these perturbations. When to this we 
add the circumstance that little reliance can be placed 
on measurements of the minute disks presented by 
the satellites, it will be seen that our estimate of the 
specific gravities of these bodies cannot by any 
means be regarded as trustworthy. 

As seen from his satellites, Jupiter must present 
a magnificent scene. To the inhabitants, if such 
there be, of the innermost satellite, he exhibits a disk 



THE MOON AND OTHER SATELLITES 205 

nearly twenty degrees in diameter. Thus, whereas 
there might be about seven hundred moons such as 
ours placed all round our horizon, the disk of Ju- 
piter, as seen from the inner satellite, could occupy 
a full eighteenth part of the horizon's circumference. 
The disk of Jupiter, as so seen, would cover a space 
on the heavens exceeding more than fourteen hun- 
dred times that which our moon covers. To the 
second satellite, Jupiter presents a disk about 12^£ 
degrees in diameter, or about six hundred times as 
large as our moon's. To the third satellite he shows 
a disk about 7| degrees in diameter, or more than 
two hundred times the size of the moon's. And, 
lastly, the inhabitants even of the furthermost satel- 
lites see him with a diameter of about 4J£ degrees — 
that is, with a disk more than sixty-five times as 
large as that of our moon. So that, if the views I 
have put forward respecting Jupiter be correct, the 
enormous space he covers on the skies of his respec- 
tive satellites must suffice to compensate in part for 
the relatively small amount of heat which he can be 
supposed capable of emitting. 

If the satellites rotate with a motion independent 
of their revolution, Jupiter passes across their skies 
like a vast moon, exhibiting phases such as those pre- 
sented by ours, but on a far vaster scale. But, be- 
sides his phases, he must exhibit to the inhabitants 
of his satellites the most marvellous picture that can 
be conceived. His belts' changes of figure and color, 
only rendered visible to our astronomers by powerful 
telescopic aid, must be distinctly visible to creatures 



206 OTHER WORLDS THAN OURS 

on Lis satellites, and cannot but afford reasoning be- 
ings on those orbs a most astounding theme for study 
and admiration. 

To the inhabitants of the satellites which circle 
around Saturn, the ringed planet must present an 
even more interesting spectacle. His disk, as seen 
from the nearest of his satellites, has a diameter of 17 
degrees, and an apparent surface exceeding more than 
nine hundred times that of the moon. From the fur- 
thest satellite his disk is less than a degree in diam- 
eter, and therefore not quite four times as large as our 
moon's. Between these limits the apparent size of 
Saturn varies as we pass from satellite to satellite; 
but from the sixth satellite his apparent surface is 
twenty-five times, while from the seventh it is six- 
teen times, as large as the moon's; so that the outer 
satellite is quite exceptionally circumstanced in this 
respect. 

It is not so much from the apparent size of his 
disk, however (though in the case of all the inner 
satellites that must be a most remarkable relation), 
as from the peculiar character of his ring-system, 
that Saturn must derive his chief interest. It is 
true that the inner satellites travel nearly in the 
plane of the rings, so as always to see them nearly 
edgewise. But, even so viewed, the rings must pre- 
sent a most striking appearance. From the inner 
satellite, indeed, the extreme span of the ring-system 
must be more than ninety degrees; 1 so that when 

1 About 93° according to the best estimates of the dimensions of the 
rings and the distance of the satellite. 



THE MOON AND OTHER SATELLITES 207 

one extremity is seen on the horizon the system 
would appear as an arch thickest in the middle, ex- 
tending over an arc of about ninety- three degrees, 
and having the disk of Saturn at its centre. When 
the whole of this arch is illuminated, Saturn is 
"full"; at other times he presents all the phases 
shown by our moon, and the arch of light is corre- 
spondingly shortened. Saturn "full" and in the 
zenith, with the ring-system dependent on either side 
of his disk, must be a glorious spectacle as seen 
from certain regions of his innermost satellite. The 
display would diminish in grandeur, though not 
perhaps in interest, as seen from satellites further 
and further away. But the inhabitants of the outer- 
most satellite of all have the privilege of seeing the 
Saturnian ring-system opened out much more fully 
than as seen from the other satellites, since the path 
of this moon is inclined some fifteen degrees to the 
plane of the ring. 

Of the satellites of Uranus and Neptune little can 
be said, because so little is known either respecting 
these orbs themselves or their primaries. I may 
remark that, despite the evidence brought forward 
to the contrary, I have very little doubt that Uranus 
has at least eight satellites. Four of those discov- 
ered by Sir W. Herschel have not indeed been yet 
identified; but one cannot read the account of his 
method of procedure without feeling that no amount 
of mere negative evidence can be opposed effectively 
to the positive information he has left respecting 
these four orbs. Indeed, when we remember that 



208 



OTHER WORLDS THAN OURS 



Uranus is twice as far from us as Saturn, while it 
has only been in recent times that the eighth Sa- 
turnian satellite (the seventh in position) has been 
discovered, we cannot but consider that in all prob- 
ability many more Uranian satellites will one day 
be discovered. Neptune also, no doubt, has a large 
family of satellites circling around him. 



CHAPTER IX 

METEORS AND COMETS: THEIR OFFICE IK THE SOLAB 

SYSTEM 

THERE are few more interesting chapters in the 
history of astronomy than that which deals 
with the gradual introduction of meteors into 
an important position in the economy of the solar 
system. Regarded for a long time as simply atmos- 
pheric phenomena (though many ancient philosophers 
held another opinion), it has only been after a long 
and persistent series of researches that they have 
come at length to be regarded in their true light. 
But, though the history of those researches is not 
only full of interest, but highly instructive and en- 
couraging, this is not the place for entering at length 
into its details. I must present facts and conclu- 
sions, rather than the narrative of observations or 
calculations by which those facts and conclusions 
have been established. Nay, it would seem at first 
sight as though even the nature of meteors could 
have very little to do with the subject of this treat- 
ise, since we cannot suppose these small bodies to be 
inhabited worlds. It will be found, however, that, 
though this is certainly true, there are reasons for 

(209) 



210 OTHER WORLDS THAN OURS 

believing that meteors are associated in a very inti- 
mate manner with the general relations of the scheme 
of worlds forming the solar system. 

Under the head "Meteors" I include all those 
objects which reach the earth's atmosphere from 
without, whether they actually make their way to 
her surface unbroken, like the aerolites; or explode 
into small fragments, as bolides and fire-balls have 
been observed to do; or are apparently consumed in 
traversing the upper regions of the air, as happens 
with shooting or falling stars. All these objects, we 
now know, represent in reality bodies of greater or 
less size, which, before their encounter with the 
earth, were travelling around the sun in orbits of 
greater or less eccentricity. The larger masses, 
though they must be very numerous (or our earth 
would not once in many ages encounter any of 
them), are yet relatively few in number as compared 
with fire -balls, and still more so in comparison with 
shooting-stars. It has been calculated, indeed, that 
these last are so numerous that the earth, in passing 
through a region of space equal to her own dimen- 
sions, must encounter no less than thirteen thousand 
of them; while of yet smaller bodies, whose passage 
through our air would only be recognizable by tele- 
scopic aid, she is supposed to encounter as many as 
forty thousand within a similar space. "Without lay- 
ing great stress on these calculations, we may yet feel 
quite sure that the earth must encounter enormous 
numbers of these bodies, from the mere fact that, 
though at any fixed station but a minute slice (so to 



METEORS AND COMETS IN SOLAR SYSTEM 211 

speak) of the earth's atmosphere is within view, and 
even but a portion only of that slice visible to a 
single observer, six or seven falling stars on the 
average may be seen during each hour of the night. 

It will be seen, then, that a problem of the utmost 
importance was involved in the question whether these 
bodies came from the interplanetary spaces, or from 
the region of space over which the earth's own attrac- 
tive energies prevail. Now that we know the former 
view to be the true one, we recognize the fact that, 
though each meteor may be individually insignificant, 
the meteors of the solar system, looked on as a single 
family, form a highly-interesting and important por- 
tion of the solar system. 

But now a yet more significant relation has to be 
considered. Eegarding meteors as planetary bodies, 
they might yet be relatively unimportant, if we had 
any reason to believe that they form a sort of zone or 
belt near the earth's orbit, resembling in a sense the 
asteroidal zone, only composed of far smaller constit- 
uent bodies. We could not then argue, from the num- 
ber of meteors encountered in a given time by the 
earth, the largeness of the total number of these 
bodies; for it might well be that this zone had no 
counterpart, either in the outer part of the planetary 
system or within the orbit of the earth. What has 
actually been discovered, however, respecting the 
paths along which the meteoric bodies have reached 
the earth, immensely enhances the importance of 
these objects. 

It has been proved, on evidence perfectly incon- 



212 OTHER WORLDS THAN OURS 

testable, that two well-marked meteoric systems travel 
in orbits of enormous eccentricity. The August me- 
teors travel on a path so eccentric that in the neigh- 
borhood of the earth's orbit it may be regarded as 
almost parabolic in figure. That it is not absolutely 
parabolic is shown, of course, by the fact that a period 
has been assigned to the revolution of the members of 
the zone. No observations have been indeed made 
by which astronomers could determine the orbit of 
these meteors, since for this purpose an exact deter- 
mination of the velocity with which they enter the 
earth's atmosphere would be requisite, while the ob- 
servations actually made to determine their velocity 
are confessedly inexact. But an association, alto- 
gether too close to be regarded as accidental, has 
been discovered between their orbit and that of a 
bright comet which appeared in 1862, and this, com- 
bined with what has since been established respecting 
the relations between comets and meteors, enables as- 
tronomers to adopt quite confidently the orbit of the 
comet as that of the meteoric system. Now, a period 
of one hundred and forty -five years implies, according 
to Kepler's law, an orbit having a mean distance nearly 
equal to that of Neptune. And since the orbit is so 
eccentric as to bring these bodies close by the earth 
when they are near perihelion, it follows that their 
aphelion distance must exceed their mean distance in 
the same degree. Hence the aphelion point of the 
August meteors must lie nearly twice as far away 
from us as the orbit of Neptune. 

The November meteors have been shown in like 



METEORS AND COMETS IN SOLAR SYSTEM 213 

manner to travel in a period of thirty-three and a 
quarter years around the sun, the aphelion of their 
orbit lying far beyond the path of Uranus. 

So far, then, as we can judge from the only two 
meteoric systems whose orbits can be said to have 
been satisfactorily determined (though there are many 
other systems which have been associated with known 
comets), we are led to the conclusion that the meteoric 
orbits are for the most part eccentric. We know, fur- 
ther, that they are inclined in all directions to the 
plane in which the earth travels, because we see that 
their constituent bodies fall upon the earth in direc- 
tions which show no tendency to near coincidence 
with the ecliptic. 

Now, these two circumstances are full of mean- 
ing. If the meteors travelled in nearly circular orbits, 
at a mean distance nearly equal to the earth's mean 
distance from the sun, then the earth would be certain 
to encounter meteors in the course of her orbital mo- 
tion round the sun. Again, if the meteors travelled 
in eccentric orbits, whose perihelia lay within the 
earth's orbit, and if these orbits all lay in or near 
the plane of the earth's path, the earth could not fail 
to encounter meteors as she travelled round the sun. 
But under the actual circumstances — the mean dis- 
tances of the meteoric orbits being in no way asso- 
ciated with the earth's mean distance, and the inclina- 
tion of these orbits to the ecliptic not being in any way 
limited — the two questions are at once suggested: 1. 
What is the a priori chance that the earth would en- 
counter the members of any meteoric system taken at 



214 OTHER WORLDS THAN OURS 

random? and, 2. If this chance be small, what is the 
conclusion to be drawn from the fact that the earth 
encounters meteors belonging to many systems? — the 
number already recognized being nearly sixty. Now, 
assigning elements at random to a meteor-system, we 
see that, unless the resulting orbit actually coincides 
with the plane of the ecliptic (a relation which would 
not happen in a million trials), the orbit will intersect 
that plane in two points, lying on a straight line 
through the sun. And, for the earth to encounter 
members of the meteoric system, it is requisite that 
one or other of these two points shall lie close to the 
earth's orbk. But these points may have any posi- 
tion whatever in the plane of the ecliptic, and the 
chance that one of them has the requisite position 
may be regarded as indefinitely small. It follows then 
that the a priori chance of the earth's encountering 
the members of a meteoric system is indefinitely small; 
and hence we conclude that the number of meteoric 
systems she passes wholly clear of is indefinitely great, 
in comparison with the number whose members she 
encounters. But she actually encounters meteors be- 
longing to no less than fifty -six systems: hence the 
total number of meteoric systems belonging to the 
planetary scheme must be an indefinitely large mul- 
tiple of the number fifty-six, or, in other words, it 
must be enormously beyond our powers of conception. 
But this being so, it behooves us to inquire, first 
of all, what extent we must assign to individual me- 
teoric systems, and how densely we may suppose 
meteoric masses to be strewn along each system; and, 



METEORS AND COMETS IN SOLAR SYSTEM 215 

secondly, what may be the nature, quality, and sub- 
stance of these meteoric masses. For we clearly 
begin to see that we are in the presence of relations 
which may — or, I should rather say, which must — 
affect most importantly the economy of the solar 
system. 

Now, we have seen something already of the lon- 
gitudinal extent of meteoric systems, since that extent 
corresponds to the circumference of meteoric orbits, 
and we have seen that these orbits have enormous 
dimensions. We may, indeed, suppose that in some 
cases the whole extent of an orbit is not occupied by 
meteoric masses at any one instant; but even when, 
as in the case of the November meteors, the annual 
displays wax and wane in splendor, there is no abso- 
lute cessation in the occurrence of star-falls on the 
date corresponding to such a system. And taking full 
account even of the marked diminution which actually 
occurs, we are yet compelled to assign an enormous 
longitudinal extent to that portion of the system 
which has been poetically termed "the gem of the 
meteor-ring." For example, in the November meteor- 
system, this portion of the ring cannot be less than 
1,000,000,000 of miles in length. As to the width of 
a meteor-system — that is, its extent in a direction 
measured in the plane of its orbit — we have no satis- 
factory information, because a meteor-system may ex- 
tend enormously on either side of the point through 
which the earth's orbit intersects it, and yet no trace 
of that extension be recognized by observers on the 
earth. Still we may conclude that this dimension lies 



216 OTHER WORLDS THAN OURS 

in extent somewhere between the longitudinal exten- 
sion of the system and the depth of the meteor-zone — 
that is, the length of a line taken through its square 
to the plane in which it lies. Now, of this last di- 
mension we can form a tolerably accurate estimate in 
many instances. We know that so long as meteors 
belonging to any system are flashing into view, our 
earth is still plunging through the system; and if we 
know the position of the system we can determine its 
depth in this way, just as we could determine the 
breadth of a range of hills if we noticed how long a 
train, travelling with known velocity, took in passing 
through a tunnel which traversed the range of hills 
in a known direction. Judged in this way, the depth 
of the November meteor-zone would seem to be one 
hundred thousand miles in the part traversed by the 
earth in 1866, about sixty thousand miles in the part 
traversed in 1867, and considerably greater (though 
the zone was more sparsely strewn with meteors) 
where the earth crossed the system in 1868 and 1869. 
Now, as regards the density with which meteors 
are strewn in any known system, I must remark on 
a mistake which has been very commonly made. It 
has been thought necessary to consider the velocity 
with which the meteors themselves travel as well as 
the earth's velocity, in order to determine, from the 
average interval of time separating the appearance of 
successive meteors, the average distance separating 
neighboring meteors from each other. This, how- 
ever, is an erroneous mode of dealing with the prob- 
lem. We need only consider the earth's velocity, 



MEIOBS AND COMETS IN SOLAR SYSTEM 217 

since the meteoric motions cannot possibly tend to 
increase the total number of encounters. 1 Let us 
apply this consideration to enable us to form a rough 
estimate of the number of bodies in the richer part 
of the November meteor-system. We may fairly as- 
sume that, taking the average of the four displays of 
the years 1866-69, the earth encountered more than 
one meteor per minute as she swept successively 
through the system; or, conveniently for our pur- 
pose, that an average distance of 1,000 miles separates 
meteor from meteor throughout the "gem of the 
ring." Now, the length of the great cluster is at 
least 1,000,000,000 miles, its thickness may be fairly 
assumed as averaging 100,000 miles, and its width 
can hardly be less than ten times its thickness, since 
the forces acting on the system tend much more 
'argely to affect its width than its thickness. Thus, 
with the assumed average of distance (1,000 miles), 
we find that the cluster cannot contain less than 
(1,000,000X100X1,000) or one hundred thousand 
million members. 

Mr. Alexander Herschel, from observations of the 
amount of light given out by these bodies, and a cal- 
culation founded on the velocity with which they 



1 Obviously the total number of meteors encountered during the 
earth's passage through a meteor-stream will be the number contained 
in a cylindrical space having a cross-section equal to the earth's, and 
traversing the meteor-stream from side to side. The motion of the me- 
teors will affect the particular set of meteors actually found within this 
space as the earth traverses it, but will not affect their number, as- 
suming a general uniformity of meteoric distribution. 

Bounce — 1 — 10 



218 OTHER WORLDS THAN OURS 

penetrate our atmosphere, has come to the conclusion 
that they must, for the most part, be very small, 
rarely, perhaps, exceeding a few ounces in weight. 
"We shall certainly not exaggerate their weight if we 
assign one-hundredth part of an ounce to each. We 
thus obtain for the weight of the whole cluster one 
thousand millions of ounces, or about twenty-eight 
thousand tons. The actual weight of the November 
meteor-system cannot, however, but enormously ex- 
ceed this amount; and therefore we recognize how 
erroneous that opinion is which an eminent astron- 
omer recently expressed, who asserted that the united 
weight of all the bodies other than planets in the solar 
system must be estimated rather by pounds than by 
tons. "We have certainly no reason for thinking that 
the November system, though one of the most impor- 
tant encountered by the earth, is exceptionally im- 
portant in the solar system. On the contrary, we 
have every reason the laws of probability can afford 
us, for believing that there must be millions of sys- 
tems equally or more extensive. And, further, the 
fall of enormous masses, many tons sometimes in 
weight, upon the earth, would point to the conclu- 
sion that the members of the November system are 
exceptionally insignificant as regards their individual 
dimensions. So that we seem forced to the conclu- 
sion that the aggregate weight of the various meteoric 
systems circulating around the sun must be estimated 
by billions of tons rather than by any of our ordinary 
units. 

I have already referred to the relation which has 



METEORS AND COMETS IN SOLAR SYSTEM 219 

been detected between comets and meteor-systems. 
Bizarre as the relation appears, it has been estab- 
lished on evidence which cannot reasonably be dis- 
puted. It carries with it results of extreme interest 
and importance. 

I do not propose here to enter into any considera- 
tion of those enormously difficult questions which are 
suggested by the study of cometic phenomena. That 
they will before very long receive their solution, I 
confidently believe; but in the present state of our 
knowledge it would indeed be hazardous to speculate 
as to what that solution may be. I may remark in 
passing, that, while I recognize in Dr. TyndalTs re- 
cently-promulgated theory on the subject the indica- 
tion of a highly-suggestive and promising line of 
research. I cannot but feel that cometic phenomena 
are far too complicated to be directly accounted for 
in the way pointed out by that distinguished physi- 
cist. Some of the more obvious, and, I may add, the 
more generally known phenomena, do indeed appear 
to receive a solution when examined under the light 
of Dr. TyndalTs researches, but numbers of others re- 
main not only unaccounted for, but standing appar- 
ently altogether opposed to his theory.' 

But for my present purpose the facts to be prin- 
cipally noticed are in a sense independent of any 
theory which may be formed respecting the nature of 



1 The theory recently put forward by Professor Tait is altogether 
inconsistent with the history of many comets. Indeed, I have been 
unable to find a single comet whose recorded changes of appearance 
countenance Professor Tait's views. 



220 



OTHER WORLDS THAN OURS 



comets. We know that the dimensions of these ob- 
jects are in many cases enormous. We know, further, 
that there must be many thousands of comets remain- 
ing undiscovered for each that our astronomers have 
detected. And, lastly, we are led to recognize the ob- 
served association between certain meteor-systems and 
certain comets as indicative of a general law by which, 
in some way as yet unexplained, comets and meteors 
are associated together. Thus, independently of the 
considerations already adduced, we are led to the con- 
clusion that meteor-systems must be very numerous; 
while from the fact that a meteor-system so important 
as the November stream is associated with a comet so 
insignificant as Tempel's, we conclude that those mag- 
nificent comets which have blazed in our skies — a 
source at once of wonder and perplexity to the as- 
tronomer — must be associated with systems of bodies 
incalculably more important than the meteor-system 
which has so often filled the heavens with falling 
stars. 

Now, combining all these results, we seem fairly 
led to the conclusion that purposes of the utmost im- 
portance in the economy of the solar system must be 
subserved by these uncounted thousands of meteoric 
streams. If, indeed, we could suppose that the plan- 
ets steered clear of them, and that the bodies compos- 
ing them simply circulated unceasingly in their orbits, 
we might form another opinion. But we know that 
meteors are continually falling upon the atmosphere of 
our own earth, either there to be dissipated into finest 
dust or to pass onward, with or without explosion, to 



s-^T 



METEORS AND COMETS IN SOLAR SYSTEM 221 

the actual surface of the earth; and we cannot doubt 
that in a similar way countless thousands of meteors 
are falling, not only upon all the primary members of 
the solar system, but upon asteroids and satellites — 
nay, are even streaming in among the minute bodies 
composing the rings of Saturn, These encounters 
cannot be wholly without result, and it is quite con- 
ceivable that most injurious consequences might ensue 
to the inhabitants of all the worlds in the solar system 
if the continual supply of meteoric matter were im- 
portantly diminished. 

Now, if meteoric masses fall continually upon the 
planets, such masses must fall in numbers inconceiv- 
ably greater upon the sun; and it is here 5 unless I 
mistake, that the great purpose of the meteoric sys- 
tems becomes apparent. 

Let us clearly recognize, however, why and how 
the sun must be assaulted by a continual inrush of 
meteoric bodies. We have seen how enormous must 
be the number of these bodies; we know how swiftly 
they travel, and on what eccentric orbits; but we 
must go further before we can prove that they fall 
upon the sun. For example, the November meteors 
are enormous in number, and travel with enormous 
velocity in a very eccentric orbit, but they do not 
approach the sun within a distance of nearly ninety 
millions of miles. Nor, indeed, can any known me- 
teoric system pour a steady hail of meteors, so to 
speak, upon the sun; for he is the ruling centre of 
every meteoric system, and therefore under ordinary 
circumstances the meteoric orbits must pass around 



222 OTHER WORLDS THAN OURS 

him, and not in such a direction as to intersect his 
substance. 

But it is to be remembered that meteors must be 
infinitely more crowded in the neighborhood of the 
sun than at a distance from him. An indefinitely 
large number of meteoric orbits must absolutely in- 
tersect in the immediate neighborhood of the sun; 
and collisions must continually be taking place as 
countless thousands of meteoric flights rush toward 
and past and then away from their perihelia. Where 
these perihelia lie close to the sun, the velocity with 
which the meteors travel must exceed two hundred 
miles per second, and therefore the collision even 
of two minute meteors must result in the genera- 
tion of an enormous amount of light and heat. But 
that is not all. Among the collisions thus con- 
tinually taking place in the sun's neighborhood there 
must be a considerable proportion in which the two 
bodies are brought momentarily almost to rest by 
the shock. In such cases the combined mass of the 
two meteors would fall directly upon the sun, a fresh 
supply of light and heat being generated as they 
were brought again to rest upon his surface. 

Whether in the continual collisions of meteors 
among themselves, and in their precipitation upon 
the sun's surface, we have a sufficient explanation 
of the seemingly exhaustless emission of light and 
heat from the sun, I should not care positively to 
assert. Professor Thompson, who was one of the 
first to adopt this view, has, I believe, abandoned it; 
though it is worthy of remark that the strongest evi- 



METEORS AND COMETS IN SOLAR SYSTEM 223 

dence in its favor has been obtained since he with- 
drew his support from it, or at least admitted that 
the downfall of meteors on the sun's surface is not 
alone sufficient to account for the solar light and 
heat. But I am quite certain that there is no flaw 
in the evidence I have adduced from the laws of 
probability; and that we are bound to accept, as a 
legitimate conclusion from that evidence, the theory 
that at least an important proportion of the sun's 
heat is supplied from the meteoric streams which 
circulate in countless millions around him. I be* 
lieve that, without adopting any unreasonable assump- 
tions, it might readily be shown that the whole even 
of that enormous supply of light and heat which the 
sun emits on every side is derived from the meteoric 
streams belonging to the solar system or drawn in 
from surrounding space, as the sun, attended by his 
family of planets, sweeps onward amid the stellar 
groups. 

If this view be correct, then the meteor-systems 
constitute, indeed, a most important part of the 
sun's domain. They may be said almost to share 
with the sun a title to be regarded as the source of 
all the forms of force which exist throughout the 
solar system. If, in the energies of living creatures 
on earth, in the forces derived from the fuel that 
propels our engines, or in the power of winds and 
storms, we trace the action of the ruling centre of 
the solar system, we may trace back the chain 
of causation yet one link further, and see in the 
sun's emission of light and heat the result of forces 



224 OTHER WORLDS THAN OURS 

inherent in the meteoric systems which circle around 
him. 

But we must not forget one most important con- 
sideration, which makes the sun (as might be antici- 
pated) again the chief source of all the forms of force 
existing within his system. The motions of the 
meteoric masses are almost wholly due to the sun's 
attraction; and therefore, in so far as those motions 
are to be regarded as a means of renewing the solar 
heat, we must regard the sun's attractive energy as 
the source whence his heat and all the other forms 
of force which he exerts are in reality derived. 

Yet one step further. The sun's attractive ener- 
gies might be increased a thousand-fold, and yet not 
avail to supply the various forms of force which are 
required by his dependent worlds, were there no 
external material on which those energies could act 
in such sort as to lead to the continual inrush of 
matter upon the solar surface. Nor would it suffice 
if such materials, even in enormous quantities, ex- 
isted close to the sun. It is the distance from which 
that material is dragged toward the sun which gives 
that orb the power of imparting those tremendous 
velocities to which the collisions of the meteoric bod- 
ies owe their real effectiveness. We thus find in 
distance, in the simple element of scale, the true 
source of the various forms of force which are con- 
tinually exerted throughout the solar system. The 
gun surrounded by millions on millions of meteoric 
masses close at hand would be powerless, but placed 
as ruler over a space far wider than the sphere 



METEORS AND COMETS IN SOLAR SYSTEM 225 

circled by Neptune's orbit, amid which space those 
countless millions of meteors are distributed, he be- 
comes forthwith the centre of a thousand forms of 
force, gathered by him continually from the systems 
of meteors circling around him, and distributed by 
him abundantly and without ceasing to his depend- 
ent worlds. 1 

It will not fail to be noticed by the thoughtful 
reader that, adopting this view of the relation in 
which meteoric and cometic systems stand with 
respect to the sun, it seems necessary that we should 
regard those planets which I have endeavored to 
raise to the dignity of secondary suns, as subordinate 
centres of attraction, around which countless thou- 
sands of meteoric systems may be supposed to circle. 
Have we any evidence pointing to such a conclusion? 

Now, there can be no doubt that if Jupiter, the 
nearest of these secondary suns, did so act upon 
a passing comet as to compel that body to circle in 
future around him, instead of pursuing its course 
around the sun, we could not in any way become 
conscious of the event unless the comet were an ex- 



1 Just as this work was about to be placed in the printer's hands I re- 
ceived from Professor Kirkwood, of America, one of his valuable contribu- 
tions to the history of the solar system. In it he points to the evidence 
we have that the sun, as he speeds onward through space, passes through 
regions in which cometic and meteoric materials are now richly, now 
sparsely strewn, and gathers in accordingly new stores of force of greater 
or less amount. The bearing of the views of this acute and soundly- 
reasoning astronomer (the Kepler of our day), not only on the theories dealt 
with in the above chapter, but on those considered, in the chapters which 
follow, will be seen at once. 



226 OTHER WORLDS THAN OURS 

ceptionally large one. I conceive, however, that 
such an event, though undoubtedly possible, 1 must 
be so uncommon that the number of cometic systems 
thus forced to own Jupiter as their centre of attrac- 
tion must be relatively few. But in another way the 
planet does exhibit his power as a comet-ruler, mak- 
ing comets recognize him as a sort of subordinate 
master, the sun being their primary ruler. When 
comets coming from outer space pass near enough 
to Jupiter, he sways them so markedly from the 
orbit they are pursuing that the scene of encounter 
becomes the aphelion of their orbit, or nearly so. 
Thence they pass on their new orbit to their peri- 
helion, returning again presently to the scene of their 
encounter with Jupiter, and so revolving in an orbit 
having its aphelion close by the orbit of Jupiter, 
until haply the giant is again near the scene of 



1 It is necessarily possible in the case of any planet, but must in many- 
cases be highly improbable. For example, astronomers sometimes assert 
that meteoric masses passing near the earth might become satellites of 
hers, but in reality this is a very unlikely event, because the maximum 
velocity which a body travelling under the earth's influence can have 
(that is, the velocity acquired by a body travelling from infinity to a perigee 
close to the earth) is less than the velocity with which a body circling on 
any orbit round the sun would move when at the earth's distance from 
him, unless its orbit were very eccentric and the aphelion close by the 
earth's orbit. Bodies travelling from outer space toward the sun cannot 
by any possibility become satellites of the earth, because they would always 
have a velocity greater than that which her attraction can master. Even 
in the rare event of their grazing her atmosphere, and so losing a large 
share of their velocity, they could not become permanent satellites of hers, 
because, returning to the scene of encounter, they would lose yet a larger 
share of their velocity, and so must be brought, and that soon, to her 
surface. 



METEORS AND COMETS IN SOLAR SYSTEM 227 

encounter at the moment when the comet comes 
back to it. In this case a fresh struggle takes place, 
the overmastering attraction of the planet necessarily 
prevailing, and the comet being often dismissed on 
a new orbit, whose perihelion, instead of its aphe- 
lion, lies close by the orbit of Jupiter. 

Now, we know that such events as these must be 
of frequent occurrence as Jupiter sweeps swiftly 
round on his orbit. For we recognize several comets 
which have evidently been compelled by Jupiter to 
take up such orbits as I have spoken of — a family 
of comets, in fact, including Encke's, Faye's, and 
Brorsen's comets, Winnecke's short-period comet, 
and several others. We judge further, from the 
laws of probability, that, for each discovered comet 
of this family, there must be thousands which have 
escaped detection. So that around the orbit of Ju- 
piter (if not around Jupiter himself) there cling the 
aphelia of myriads of cometic orbits, whose peri- 
helia lie at all conceivable distances from the sun 
less than the distance of Jupiter. 

Saturn also has his family of comets; so also 
have Uranus and Neptune. The comet associated 
with the November meteors belongs indeed to the 
Uranian comet-family, and the epoch (126 A.D.) has 
even been pointed out when this comet fell under 
the dominion (subject always to the sun's superior 
control) of that distant planet. 

And here I may refer to a view which I have long 
entertained respecting the purposes which meteoric 
and cometic systems have fulfilled in the past history 



228 OTHER WORLDS THAN OURS 

of the solar system. 1 We know that the materials 
composing meteors, and we conclude, - therefore, that 
those composing comets, do not differ from those 
which constitute the earth and sun, and presumably 
the planets also. Therefore, under the continual rain 
of meteoric matter, it may be said that the earth, sun, 
and planets, are growing. Now, the idea obviously 
suggests itself, that the whole growth of the solar 
system, from its primal condition to its present state, 
may have been due to processes resembling those 
which we now see taking place within its bounds. 
It is of course obvious that, if this be so, the num- 
ber of meteoric and cometic systems must have been 
enormously greater originally than it is at present. 
Countless millions of meteoric systems, travelling in 
orbits of every degree of eccentricity and inclination, 
travelling also in all conceivable directions around the 
centre of gravity of the whole, would go to the mak- 
ing up of each individual planet. A marked ten- 
dency to aggregate around one definite plane, and 
to move in directions which, referred to that plane, 
corresponded to the present direction of planetary 
motion, would suffice to account for the present state 
of things. The effect of multiplied collisions would 



1 Since the present chapter was written, I find that the hypothesis here 
put forward, has, in a general way, been touched on by more than one 
astronomer and physicist. I believe, however, that here, for the first 
time, it has been associated with the chief features of the solar system. 
It was suggested in note B (Appendix) to my treatise on Saturn. But, as 
a matter of fact, when that note was written, as also when those passages 
were published in which the same hypothesis is touched by other authors, 
the decisive evidences in favor of the theory were wanting. 



METEORS AND COMETS IN SOLAR SYSTEM 229 

necessarily be to eliminate orbits of exaggerated 
eccentricity, and to form systems travelling nearly 
on the mean plane of the aggregate motions, and 
with a direct motion. Further, where collisions were 
most numerous, there would be found not only the 
most circular resulting orbits, not only the greatest 
approach to exact coincidence of such orbits with the 
mean plane of the whole system, but the bodies 
formed out of the resulting systems would there 
exhibit rotations coinciding most nearly with the 
mean plane of the entire system.' 

It seems to me that, not only has this general 
view of the mode in which our system has reached 
its present state a greater support from what is now 
actually going on than the nebular hypothesis of 
Laplace, but that it serves to account in a far more 
satisfactory manner for the principal peculiarities of 
the solar system. I might indeed go further, and say 
that, where these peculiarities seem to oppose them- 
selves to Laplace's theory, they give support to that 
which I have put forward. 

For example, what is there in the nebular hypoth- 
esis which affords even a general explanation of the 
strange varieties of size observed in the planetary 
system? How can that hypothesis be reconciled with 
the remarkable variations of inclination observed 



1 This conclusion depends on a well-known law of probability. It 
may be thus illustrated: If we have in a bag a hundred white and a 
hundred black balls, and take out at random a number of balls, then the 
larger that number, the more nearly (in all probability) will the number 
of black and white balls included in it approach to a ratio of equality. 



230 OTHER WORLDS THAN OURS 

among the planets, or with the retrograde and al- 
most perpendicular motion of the satellites of Uranus? 
Nor, again, is the hypothesis consistent with the 
observed peculiarities of motion of those meteoric 
systems which we must now regard as regular mem- 
bers of the solar system. 

Now, according to the hypothesis I have put for- 
ward above, a general explanation of all these mat- 
ters is at once suggested. Let us consider: 

In the neighborhood of the great central aggrega- 
tion which would undoubtedly result from the mo- 
tions of such meteoric systems as I have considered, 
all the motions would be very rapid. They would, 
in fact, resemble the motions now actually observed 
in the sun's neighborhood. Here, therefore, subor- 
dinate aggregations would form with difficulty, since 
they would have small power of overruling meteoric 
systems rushing with so great a velocity past them. 
In the sun's immediate neighborhood, then, we should 
expect to find relatively small planets; and we do 
accordingly find that Mercury, nearest to him, is the 
smallest of the planets, Yenus larger, and the earth 
(yet further away) not only larger than Venus, but 
adorned with an attendant satellite. 

Now, at a much greater distance from the sun the 
meteoric motions would be so much less, that here, 
supposing only a suitable mean density of aggrega- 
tion, it would be possible for subordinate centres of 
aggregation of far greater magnitude to form. These 
centres would increase in importance as they swept 
round the central aggregation, continually gathering 



j 



METEORS AND COMETS IN SOLAR SYSTEM 231 

fresh recruits. Indeed, though, as now, they would 
not be able to prevent the major part of the mate- 
rials rushing from outer space toward the sun from 
aggregating round him, they would still gather in no 
inconsiderable portion of those materials. Where the 
largest portion would be gathered would depend on 
the way in which (taking a general view of the sys- 
tem) the quantity of material increased toward the 
neighborhood of the centre. For clearly, while dis- 
tance from the sun would increase the facility with 
which materials would be gathered in — since the sun's 
influence would diminish with distance, it would also 
affect the quantity of material available — since, from 
a very early period, the system must have begun to 
show an appearance resembling that now presented 
by the zodiacal light, that is, a general increase of 
density toward the centre. 

Assuming that the region of maximum aggrega- 
tion was that where the influence of the ruling centre 
first became so far diminished with distance as to 
render the formation of a great subordinate aggrega- 
tion possible, we should have the innermost of the 
outer series of planets also the most bulky; and 
next, within that giant planet we should find a rela- 
tively barren space, cleared of material not only by 
the sun's still powerful influence, but also by the 
influence of this first important subordinate aggre- 
gation. The initial assumption is, in itself, at least 
not improbable, and, having once admitted it, we 
find an explanation of the giant mass of Jupiter, of 
the comparative poverty of material just within the 



232 OTHER WORLDS THAN OURS 

orbit of Jupiter, and hence, of the condition of the 
asteroidal zone, and of the smallness of the planet 
Mars next within that zone — though this planet far 
outweighs (according to Leverrier's estimate) the 
united mass of all the asteroids. Beyond the orbit 
of Jupiter, we should expect (after passing an enor- 
mously wide space, bare of worlds) to find still a 
great abundance of material, and an even greater 
facility in the aggregation of that material. Thus 
the existence of the planet Saturn, next in impor- 
tance to Jupiter, and surpassing him in the com- 
plexity of his attendant system, is accounted for; yet 
further away we look for and find still an abun- 
dance of material, and that material somewhat more 
uniformly strewn, while the sun's small influence is 
indicated by the existence of satellites, of which 
doubtless many more will one day be discovered by 
astronomers. 

And as to the rotations of the various members 
of the solar system we find some account, necessarily 
not exact, given by this theory. I have mentioned 
above the results to be looked for; those observed 
are closely accordant with that view. Thus the sun, 
the largest member of the system, and specially pre- 
eminent within its inner division, rotates on an axis 
inclined but about seven degrees to the mean plane 
of the system. Mars, the least member of this sys- 
tem, has an inclination of no less than twenty-eight 
degrees; the larger earth an inclination of but 
twenty-three degrees. The inclinations of Venus and 
Mercury are undetermined; they may be expected 



METEORS AND COMETS IN SOLAR SYSTEM 233 

to be large, not merely on account of the smallness 
of these bodies, but on account of their proximity to 
the sun. Of the outer division of the system, Ju- 
piter, the largest, has an inclination of little more 
than three degrees; Saturn has a very considerable 
inclination (more than twenty -six degrees); Uranus 
has an inclination which may be described as act- 
ually greater than ninety degrees, since he rotates 
backward with his equator inclined seventy-six de- 
grees to the ecliptic. And lastly, if the observations 
hitherto made on Neptune's satellites are to be 
trusted, this planet, probably, rotates in a retro- 
grade manner, his equator being inclined some 
twenty-six degrees to the horizon; so that, to render 
the comparison between his rotation and that of the 
other members of the solar system complete, he may 
be said to rotate in a direct manner with his equator 
inclined some one hundred and fifty -four degrees to 
the ecliptic. 

The great inclination and eccentricity of many of 
the asteroidal orbits are also accounted for more 
satisfactorily by this theory than by the nebular 
hypothesis. In fact, there is an absolute incorrect- 
ness in the assertion that the smallness of the aste- 
roids can (on the ordinary view of their origin) ex- 
plain the relatively irregular nature of their motions. 
Their minuteness doubtless brings them more under 
the disturbing influence of Jupiter than a single 
massive planet at the same distance from the sun 
would be. But the attractions of Jupiter can have 
no influence in causing the asteroids to depart so 



234 OTHER WORLDS THAN OURS 

widely as they do from the ecliptic, since his path 
lies quite close to the ecliptic, and even nearer to 
the mean plane of the solar system. But bodies 
formed as the asteroids are supposed to be, according 
to the hypothesis I have suggested, would neces- 
sarily exhibit a much greater variety of motion than 
would be recognized in the case of the larger planets. 

Another point in which, as I conceive, my hy- 
pothesis is more satisfactory than the nebular one, 
consists in the fact that it suggests an explanation 
of the peculiarities observed in the planetary periods. 
Professor Kirkwood's researches into the various 
relations of commensurability presented among the 
periods of planets and satellites, and the known 
effects of commensurability in encouraging the accu- 
mulation of planetary perturbations, will at once 
suggest to the mathematical reader the way in which 
a system, forming in such a manner as I have im- 
agined, might be expected to exhibit the presence 
of law as regards distances and periods. I know of 
nothing in the nebular hypothesis which encourages 
the belief that a system framed as Laplace conceived 
the solar system to be, would exhibit any such laws 
as are found within the planetary scheme. 

The hypothesis I have put forward also gets rid 
of that which has always seemed to me the great dif- 
ficulty of the nebular hypothesis. According to the 
views of Laplace, Neptune must have been formed 
millions of ages before Uranus, Uranus as long be- 
fore Saturn, Saturn as long before Jupiter, and so 
on. Now, we know that the appearance of those 



METEORS AND COMETS IN SOLAR SYSTEM 235 

primary members of the solar system which we are 
best able to study does not indicate any such enor- 
mous disproportion in the ages of the planets, even 
if it does not indicate that the planets were formed 
nearly at the same era. According to my hy- 
pothesis, the various processes of aggregation would 
go on simultaneously (just as the influences which 
Jupiter has on comets are now exerted simultane- 
ously with those more powerful influences possessed 
by the sun); and though the various orbs formed by 
those processes would not necessarily be completed 
simultaneously, there would be no such enormous 
disproportion in their age as is necessary according 
to the theory of Laplace. 

Yet another strong point in favor of this hypoth- 
esis resides in the circumstance that we now have 
every reason to believe that all the planets are con- 
stituted of the same elements. When it was thought 
that Jupiter might be a watery globe, for instance, 
there was some evidence in favor of Laplace's theory. 
But we now know that Jupiter is not constituted dif- 
ferently, in all probability, from the earth and sun, 
as according to Laplace's theory he must have been. 
Since, then, we know that meteors contain the same 
elements which exist in the constitution of sun and 
planets, we have here a very strong argument in 
favor of the view that they have played the impor- 
tant part I have assigned to them in the formation 
of the solar system. 

But, after all, the strongest evidence in favor of 
the hypothesis I have suggested, consists in the fact 



236 OTHER WORLDS THAN OURS 

that the processes by means of which I conceive the 
solar system to have been formed are undoubtedly 
going on before our eyes. There may be little, in- 
deed, in the downfall of meteoric showers to suggest 
the idea of world -formation or sun-formation; little 
in the present aspect of the zodiacal light or of the 
solar corona to present to the mind's eye a picture 
of that vaster agglomeration of meteoric and cometic 
systems, all speeding with inconceivable velocities 
on their interlacing orbits, which I imagine to have 
been the embryon of the solar scheme. But sun and 
planets are growing, however slowly, as the meteoric 
hail falls continuously upon them; the zodiacal light 
and the solar corona are doubtless due to the exist- 
ence of meteoric systems, resembling (however rela- 
tively insignificant) those which I have pictured as 
the materials of the planetary scheme. In the Sa- 
turnian rings, also, which have been proved by the 
researches of Maxwell and others to consist of multi- 
tudes of discrete bodies, we have evidence of the 
same sort in the case of a subordinate centre of ag- 
gregation. So that we have a form of evidence which 
was wanting in the case of the nebular hypothesis, 
in favor of this other hypothesis, by which, as in 
Laplace's, the present state of the solar system is 
regarded as the result of a process of development, 
and not of special creative fiats of the Almighty. 

In this last respect, the hypothesis I have put for- 
ward will doubtless seem objectionable to those who 
imagine that, in indicating processes according to 
which the solar system may have reached its present 



METEORS AND COMETS IN SOLAR SYSTEM 237 



condition, astronomers are attacking the attributes of 
God. This will be the more unfortunate, because 
those who entertain this strange view may be re- 
garded as probably so far beyond the reach of argu- 
ment as to be unlikely ever to abandon their objec- 
tion. Otherwise, it might avail to point out that, as, 
in all that surrounds us, we find God acting through 
second causes, we can have no reason for assigning 
limits to the range of space or time within which 
He so acts; that is, we can have no reason for be- 
lieving that we can point to a time when He acted 
directly upon the universe: and further, that it gives 
an altogether higher idea of that wisdom which must, 
in any case, be far above our conceptions, to regard 
the laws of God as so perfect that they operate 
always to work out His will — without the necessity 
of special interference on His part —than to see His 
hand directly operative in all th', phenomena of the 
universe. 



CHAPTSB X 

OTHSB SUNS THAN OURS 

WE are now to venture into regions where we 
shall no longer have clear lights to guide 
us. Tremendous as are the dimensions of 
the solar system, the widest sweep of the planetary 
orbits sinks into insignificance compared with the 
distances which separate from us even the nearest 
of the fixed stars. From beyond depths which the 
human mind is utterly unable to conceive there come 
to us the rays of light which myriads of those orbs 
are pouring forth, and it is from the lessons taught 
us by these light-rays that we are to form our ideas 
concerning the nature of the orbs which emit them. 
Very carefully and cautiously must we proceed, if 
we would avoid being led into vain imaginings. It 
will but mislead us to pass a single step beyond the 
path which is dimly lighted for us, and yet that path 
is so narrow and so obstructed with difficulties, that 
we find ourselves continually tempted to leave it, 
and to venture forward on the alluring and easy 
paths which speculation opens out on every hand 
around us. 
(238) 



OTHER SUNS THAN OURS 239 

And yet we may well remain content to listen 
only to the teachings of known facts. Even so re- 
straining ourselves, we have in reality a wide and 
noble domain to explore. Facts which seem sever- 
ally unimportant are found, when considered as 
parts of a grand whole, to indicate relations so im- 
pressive and so interesting, that the revelations of 
the telescope within the solar system are apt to seem 
commonplace beside them. We have, in fact, to con- 
sider no longer the structure of a system — the archi- 
tecture of the universe is our theme. 

Let us examine carefully the evidence which 
science, has gathered together for us, endeavoring at 
each step to gain the full amount of knowledge the 
several facts involve, while, at the same time, cau- 
tiously refraining from any attempt to overstep the 
bounds indicated by our evidence. 

In the first place, let us consider what may be 
learned from the analogy of the solar system. The 
study, is an inviting one, since the discoveries on 
which we are to found our views have been made so 
recently, that the subject has all the charm of nov- 
elty and freshness, while it involves the considera- 
tion of the soundest and most instructive mode of 
pursuing our researches. 

We have seen in the solar system a variety and 
complexity of structure such as, half a century ago, 
few astronomers would have thought of ascribing to 
it. When Sir William Herschel began that noble 
series of researches amid the sidereal depths by which 
his name has been rendered illustrious, he saw in 



240 OTHER WORLDS THAN OURS 

the solar system a scheme very different indeed from 
that which is presented to our contemplation. He 
beheld a vast central body, surrounded by a limited 
number of orbs, some of which were the centres of 
subordinate schemes of greater or less extent. When 
we have added the ring of Saturn as the only forma- 
tion differing from planets and satellites in character, 
and the comets few and far between, which seemed 
rather accidental tributaries of the sun than regular 
members of his family, we have considered all the 
features which the solar system, as known in Sir 
William Herschel's day, presented to the contem- 
plation of astronomers. 

With us it is very different. We see that there 
exists within the solar system a variety of size and 
structure, of motion, arrangement, and aggregation, 
which is already inconceivable, and yet doubtless 
but faintly shadows forth the real complexity and 
richness of the scheme swayed by our sun. Perhaps 
it is in considering the solar system in the particular 
light in which, in this treatise, I have had occasion 
to present it, that this wonderful variety of confor- 
mation is made most strikingly apparent. But, apart 
from all speculative theories, there can be no doubt 
that the solar system presents to us a subject of 
study amazing in itself, but most amazing when we 
regard it as supplying the analogies which are to 
guide us in forming our views respecting the side- 
real system. Besides the family of planets circling 
round the sun, besides the system of dependent orbs 
which circle round the planets, we see a zone in 



^ 



OTHER SUNS THAN OUBS 241 

which independent planets circle by hundreds, per- 
haps even by myriads, round the solar orb; we see 
the ring of Saturn composed of thousands of tiny 
bodies; we see the meteoric systems in countless 
hosts; we see the comets of our scheme in millions 
on millions; and less certainly, but still not indis- 
tinctly, we recognize the existence of a multitude of 
new and hitherto unsuspected forms of matter within 
the circle of our sun's attraction. 

What opinion, then, are we to form — even here, 
at the very outset of our inquiry — respecting the 
sidereal scheme of which our sun forms but a unit? 
Surely it would be to lose sight of the significant 
lesson taught us by the solar system, it would be to 
forget how sure and safe a guide the greatest of 
modern astronomers found in the teachings of anal- 
ogy, to adopt the same view now which that great 
astronomer adopted a century ago. If, viewing the 
solar system as consisting of discrete orbs, compar- 
able one with another in size, and distributed not 
without a certain uniformity around their ruling 
centre, Sir William Herschel held that the sidereal 
scheme presented somewhat similar relations, surely 
we, who know certainly that the solar system is con- 
stituted so differently, must adopt a far different view 
of the sidereal scheme also. 

Let us remember that there is here — so far as our 
respect and admiration for Sir William Herschel are 
concerned — a choice between two courses. Assuming, 
as indeed is just, that the views of our great men 
are not rashly to be thrown on one side, we have to 

SCIENCE— 1—11 



242 OTHER WORLDS THAN OURS 

choose whether we would rather abandon the views 
which Sir William Herschel formed about facts, or 
the views which he formed about principles. If we 
accept his opinion (or rather, after all, his mere sug- 
gestion) that the stars are tolerably uniform in magni- 
tude and distribution, we must abandon the analogy 
of the solar system. If, on the contrary, we accept 
Sir William Herschel's often-expressed opinion that, 
in theorizing about the unknown, there can be no 
safer guide than the analogy of known facts, we must 
abandon the view (which seemed to him but prob- 
able) that the stars are distributed with tolerable 
uniformity throughout our galaxy, and are compar- 
able inter se in magnitude and splendor. 

There can be no doubt which course is prefer- 
able. We know certainly that Sir William Herschel 
was often mistaken, as all men must be, in matters 
of fact; while we know with equal certainty that he 
owed the marvellous success with which he theorized, 
to his adoption of the principle that analogy is the 
chief and the best guide for the student of astronomy. 

We are compelled, then, in our very respect and 
admiration for the greatest astronomer of modern 
times, to regard the constitution of the sidereal sys- 
tem as, in all probability, very different from what 
he imagined. 

We must be prepared to expect an infinite variety 
of figure, of structure, of motion, and of aggregation 
throughout the galactic scheme. If some orbs within 
that scheme seem probably to be suns like our own, 
we must not be surprised to find others which are 



OTHER SUNS THAN OURS 248 

probably far larger or far smaller. We may look for 
objects differing as much from the suns of the side- 
real system as the asteroidal zone differs from Saturn 
or from Jupiter. So that, if we should recognize 
evidence of the existence of clusters of minute stars 
— a whole cluster, perhaps, not equalling in real im- 
portance the least of the suns of the system — we may 
accept that evidence without any scruples suggested 
by the improbability of the conclusion to which it 
points. Again, we may expect to find schemes within 
the sidereal system, differing as much from discrete 
stars or star-clusters as the rings of Saturn differ 
from the primary planets or from the asteroidal zone. 
So that, if we should recognize evidence of the ex- 
istence of relatively minute clusters, whose compo- 
nents are either so small or so closely aggregated as 
not to be separately visible even in our most power- 
ful telescopes, this evidence may fairly be accepted 
as accordant with the only analogy we have for our 
guidance. Yet once more: we may look for systems 
differing as much from all ordinary star-clusters as 
the eccentric and far-reaching meteor-systems differ 
from the symmetrical rings of Saturn. So that, if we 
should find evidence of strange schemes within the 
sidereal system, schemes presenting every bizarre va- 
riety of figure, with strange complexities of spiral 
whorls or outlying branches, losing themselves, as it 
were, in the depths toward which they seem to ex- 
tend—this also need not surprise us: we need not 
conclude that here, at any rate, we are looking be- 
yond the bounds of the sidereal system, and gazing 



244 OTHER WORLDS THAN OURS 

upon external galaxies, for the analogy we have 
chosen for our guidance teaches us that such struc- 
tures were to be expected within the scheme of 
which our sun is a component. And, finally, if we 
should find reason to assure ourselves that there are 
objects in the depths of space whose very substance 
and constitution are different from those of all other 
objects within the sidereal system, we need by no 
means believe that the objects thus singularly consti- 
tuted belong to, or form, external systems. For the 
millions on millions of comets which form part and 
parcel of the solar system present a precisely analo- 
gous difference of structure, as compared with the 
other members of that system. 

Having thus replaced the erroneous analogies to 
which — through no fault of his own — Sir William 
Herschel was led to look for guidance, by the more 
trustworthy analogies which the recent progress of 
astronomy has afforded for our instruction, we may 
proceed to consider the direct evidence we have 
respecting the constitution of our galaxy. 

In the first place, let us examine the evidence 
which points to the dimensions of the sidereal 
system. 

That the nearest members of the system lie at 
enormous distances from us is proved by the fact 
that, as the earth sweeps on her vast orbit round the 
sun, no appreciable change is observed in the con- 
figuration of the star-groups. That a circle having 
a diameter of more than one hundred and eighty 
millions of miles should be swept out year by year 



OTHER SUNS THAN OURS 246 

as the eaUh traverses her orbit, and yet that the sur- 
rounding stars should exhibit no change of place, is 
at once the most striking and the simplest evidence 
we have of the enormous scale on which the sidereal 
system is constructed. And yet this first obvious 
fact sinks almost into insignificance when we regard 
thoughtfully the teaching of modern instrumental 
astronomy. There might be a real shifting of ap- 
parent position which yet the unaided eye would fail 
to detect, and such a change would indicate distances 
so enormous that the mind fails altogether to con- 
ceive their real significance. But the exact instru- 
ments of modern times would exhibit a change of 
place infinitely more minute than any which the un- 
aided eye could recognize. If a star shifted by so 
much as the ten-thousandth part of the moon's ap- 
parent diameter, modern astronomers could assure 
themselves of the change of place. And when we 
remember that in precisely the same proportion that 
we increase the exactitude of instrumental observa- 
tion we increase also the significance of the stars' 
apparent fixity of position, it will be seen at once 
how astounding is the lesson conveyed by the fact 
that all but a very few indeed of the stars remain 
absolutely unaffected — even under the most powerful 
instrumental examination — by the enormous range of 
the earth's orbital motion. 

We can roughly estimate the distances of the few 
stars which are thus affected, and thence — on the 
hypothesis that the intrinsic brilliancy of their light 
is the same as the sun's — we may form some idea of 



246 OTHER WORLDS THAN OURS 

their dimensions. I shall, however, only apply this 
process, in detail, to a single case, because my pres- 
ent object is rather to indicate in a general way the 
scale on which the sidereal system is constructed, 
than to enter at length on the more exact details 
which find their place in ordinary treatises on 
astronomy. 

The star Alpha Centauri is one of the brightest 
in the heavens, Sirius and Canopus alone surpassing 
it in splendor. But it is not its exceptional bril- 
liancy alone which led astronomers to regard it as 
likely to afford evidence of an apparent change of 
place corresponding to the earth's real change of 
place as she sweeps round her orbit. Of course, 
the brightest stars are presumably the nearest; but 
there is another indication of proximity at least 
equally important. The so-called fixed stars are in 
reality slowly moving onward on definite courses — 
slowly, that is, in appearance, though in reality 
their motions are doubtless inconceivably rapid. 
Now, these motions, the proper motions of the stars, 
as they are called, are as yet very little understood. 
We know only that the whole of the galactic system 
is astir with life, but whither the orbs are severally 
tending we are not yet able to say. Nor do we 
know what portion of the stellar motions may be 
due to the undoubted proper motion of our own sun 
through space. This, however, may be regarded as 
certain, that, until we know something respecting the 
laws which regulate the stellar movements, we must 
regard the magnitude of a star's motion as probably 



OTHER SUNS THAN OURS 247 

an indication of relative proximity. Precisely as a 
man walking at a great distance from us appears to 
move much more slowly than one who is walking 
at the same rate close by, so the apparent rate of a 
star's motion is diminished in proportion to the star's 
distance from us. When, therefore, it was found that 
the star Alpha Centauri is moving more rapidly than 
other stars, this fact, combined with the great lustre 
of the star, led astronomers to suspect that it must 
be comparatively near to us. 

Observations, made to determine whether the star 
shows any sign of an annual change of place corre- 
sponding to the earth's annual orbital motion, were 
rewarded by the detection of a very appreciable dis- 
placement. In fact, owing to the motion of the 
earth, each year, in a nearly circular orbit one hun- 
dred and eighty million miles in diameter, the star 
Alpha Centauri appears to trace out each year a 
minute oval path on the celestial sphere, the greater 
axis of the oval being equal in length to about sfoth 
part of the moon's apparent diameter. 1 

It follows from this that, in round numbers, the 
distance of Alpha Centauri from us is about twenty 
millions of millions of miles. The distance of the 
earth from the sun shrinks into insignificance beside 
this enormous gap. Even Neptune, though circling 
round the sun at a distance three hundred times 



1 It hardly need be mentioned, perhaps, that this motion being super- 
added to the star's more considerable proper motion, the path which the 
star seems really to follow is a looped one, the size of each loop being 
small in comparison with the distance between successive loops. 



248 OTHER WORLDS THAN OURS 

vaster than that which separates us from that lumi- 
nary, is jet relatively so much nearer than Alpha 
Centauri, that a sun filling the whole orbit of Nep- 
tune would appear, as seen from that star, but about 
one-ninth as large as the sun appears to us. 

Now let us consider what dimensions we may 
assign to Alpha Centauri, on the assumption that the 
surface of this star emits a light as brilliant as that 
which proceeds from the photosphere of our own 
sun. We must not neglect the consideration that 
the star is double — the companion emitting perhaps 
about one-sixteenth as much light as the primary. 1 
The distance of Alpha Centauri is equal to about 
two hundred and thirty thousand times that which 
separates us from the sun. Therefore, if removed 
to the star's distance, the sun would shine with 
only 68,900,000,000 ^ part of his present brilliancy. Now, 
according to the most careful estimates of the bril- 
liancy of Alpha Centauri, the light we receive from 
that star is about 16,950,000,000 th of that we receive from 
the sun. a It follows, therefore, that the star emits 
about three times as much light as the sun; and 
therefore, so far as the emission of light is a crite- 
rion of size, the star may be regarded as consider- 
ably larger than our own sun. In fact, reducing the 

1 Sir John Herschel, observing the star with his twenty -foot reflector, 
thought the secondary brighter than it is usually considered. I cannot 
but think that, for a comparison of this sort, smaller telescopes may more 
safely be trusted. 

2 This estimate is founded on Sir John Herschel's comparison between 
the light of the star and that of the full moon, and Zollner's comparison 
between the light of the full moon and that of the sun. 



OTHER SUNS THAN OURS 249 

total light of the pair by one -sixteenth, we find that 
the primary must still emit about three times as 
much light as the sun, and therefore the diameter 
of the star, as thus estimated, would appear to 
exceed our sun's in the proportion of about seven- 
teen to ten. 

We have here, then, clear and decisive evidence 
in favor of the view that among the fixed stars there 
are orbs which may be regarded as veritable suns, 
worthy to be the ruling centres of schemes as noble 
as the solar system. For we know quite certainly 
that the greater number of the first-magnitude stars 
are very much further from us than Alpha Centauri, 
with which, however, they are fairly comparable in 
brilliancy: so that they may be regarded as for the 
most part at least equal to that star in size and mass. 
Sirius and Canopus, indeed, must far surpass Alpha 
Centauri. The latter, though more than thrice as 
bright, exhibits no appreciable change of position 
as the earth circles round the sun. Sirius, which is 
more than four times brighter than Alpha Centauri, 
shows an annual change of position which certainly 
does not exceed one-fourth of that star's. It is 
therefore four times further from us than Alpha 
Centauri, and, did it emit no greater amount of 
light, would appear to shine with but one-sixteenth 
of that star's lustre. As in reality it is four times 
as bright, the real amount of light it emits must 
exceed that of Alpha Centauri no less than sixty- 
four times, and that of our own sun no less than one 
hundred and ninety -two times. So that, judged from 



250 OTHER WORLDS THAN OURS 

this indication alone, the diameter of Sirius may be 
held to exceed that of our sun in the proportion of 
about fourteen to one, an estimate which assigns to 
Sirius a diameter of nearly twelve million miles, and 
a volume two thousand six hundred and eighty -eight 
times as large as the sun's. 

But, on the other hand, still confining our atten- 
tion to this method of estimating magnitude, we find 
reason for believing that many of the visible stars 
must fall far short of our sun in magnitude. The 
sixth-magnitude double star, 61 Cygni, has been 
found to be nearer to us than Sirius, and about 
three times as far from us as Alpha Centauri. Now, 
we may assume that each component sends us about 
one-hundredth part of the light we receive from 
Alpha Centauri; it follows that the latter star, if 
removed to the distance at which 61 Cygni lies from 
us (when its light would of course be diminished to 
one-ninth of its present value), would outshine either 
component of that double star more than eleven 
times; hence (on the assumption that brightness is 
a fair measure of real dimensions), each component 
has a diameter less than one-third that of Alpha 
Centauri. We may roughly estimate the volume of 
each at about &th of that of the latter star. So that, 
remembering what has already been shown respecting 
the relation between Alpha Centauri and our sun, 
the two suns which form the double star 61 Cygni 
would each have a diameter equal to about $$ths of 
the sun's, and a volume equal to about Aths. The 
sum of their volumes would be therefore about one- 



OTHER SUNS THAN OURS 251 

third of his; and it will presently appear that a per- 
fectly distinct mode of estimation tends to show that 
the sum of their masses bears about the same pro- 
portion to the sun's mass. 

But here at once we have evidence that there is 
a very wide range of magnitude among the fixed 
stars. We have seen reason to believe that Sirius is 
twenty-six hundred and eighty-eight times as large 
as the sun, while each of the suns forming the 
double star 61 Cygni would appear to have a vol- 
ume less than one-fifth of our sun's, and therefore 
less than n&n?th of the volume of Sirius. So that, 
by considering only three cases, we have found tol- 
erably clear evidence of a range of variety in vol- 
ume, reminding us forcibly of that which we recog- 
nize in the solar system. We cannot suppose that 
these three cases, which have been selected at ran- 
dom — so far as the question of volume is concerned 
— indicate anything like the real limits within which 
the fixed stars differ in magnitude. So that we may 
confidently accept, as the most probable conclusion 
from the evidence before us, that the range of real 
magnitude among the fixed stars is very far greater 
than Sir W. Herschel was led to anticipate, when, 
nearly a century ago, he began his researches into 
the sidereal system. 

But it is not sufficient that we should thus form 
an estimate of the nature of the fixed stars, from the 
amount of light they send to us. It is desirable — 
and fortunately it is practicable — to obtain informa- 
tion as to the absolute mass or weight of some of 



252 OTHER WORLDS THAN OURS 

the fixed stars, and further to ascertain of what sub- 
stances they may be composed, and in what condi- 
tion those substances may exist. Mere lights, how- 
ever glorious, or however wide the sphere within 
which they displayed their splendors, would not be 
fit to sway the motions of orbs resembling those 
which circle around our sun. Nor would such 
lights serve to indicate to the astronomer that, out 
yonder, myriads of millions of miles beyond the ex- 
treme limits of the solar system, there exist materials 
suited to form the substance of worlds resembling our 
own. 

It seems a strange circumstance that astronomers 
should be able to form a more exact and trustworthy 
estimate of the weight of certain fixed stars than they 
can hope to form respecting the volume of any of 
those bodies. Let us consider what evidence we have 
on this point. 

I have spoken of the star 61 Cygni as a double 
star. The smaller star shows very clear indications 
of orbital motion around its primary. That the two 
are associated together, and not merely seen, as it 
were by an accident, nearly in the same line of 
view, is indeed certain, because that peculiarly large 
proper motion already referred to is shared in by 
both. But many stars may be physically associated, 
and yet the distance really separating them may 
enormously exceed that by which they seem to be 
separated — since the line joining them is not neces- 
sarily square to the line of sight. The components 
of the star 61 Cygni have been carefully watched, 



OTHER SUNS THAN OURS 258 

however, and their motions show that they are cir- 
cling around each other. The distance separating 
them is probably about half as large again as the 
distance of Neptune from the sun. 

The period of revolution appears to be about five 
hundred and twenty years, which is more than three 
times as great as the period of Neptune. Now, we 
know that a planet placed at a distance from the sun 
equal to that which separates the components of 61 
Cygni, would occupy a much less period than five 
hundred and twenty years in completing a revolu- 
tion; in fact, its period would be about three hun- 
dred years. Hence it follows that the components 
of 61 Cygni are attracted together less forcibly than 
Neptune is attracted toward the sun, and therefore 
that the sum of their masses must be less than the 
sun's mass. It is easy to compute the actual pro- 
portion, and we find accordingly that the two com- 
ponents of 61 Cygni, taken together, weigh about 
one-third as much as our sun. 1 

The star Alpha Centauri is also a binary system, 
and, though it has not been so systematically ob- 
served as 61 Cygni, some astronomers believe that 
its period has been even more satisfactorily deter- 
mined. Indeed, there are peculiarities in the mo- 
tion of 61 Cygni, which, without throwing doubt on 
the general conclusions deduced above, yet suggest 

1 It may easily be shown that, if a pair of bodies, circling around each 
other at a certain distance, take a certain time T in effecting a revolution, 
while another pair at the same distance take a time t, the former pair, 
taken together, have a weight which bears to the weight of the latter pair 
the ratio of <* to T». 



254: OTHER WORLDS THAN OURS 

that a third (probably opaque) orb affects the mo- 
tions of the other two. From a careful comparison 
of all the observations made in recent times on 
Alpha Centauri, Mr. Hind has assigned to the com- 
ponents a period of revolution of about eighty-one 
years, and a mean distance of 13.6 seconds of arc, 
corresponding to a real distance exceeding the earth's 
distance from the sun some fifteen times. Since a 
planet placed at this distance from the sun would 
occupy less than sixty years in completing a revolu- 
tion around that body, it follows that the mass of 
the two components of Alpha Centauri must be less 
than that of the sun. This result (if the data be 
considered trustworthy) would indicate a consider- 
able difference between the condition of the star and 
that of our sun; for we have seen that the star gives 
out much more light than the sun. However, I be- 
lieve that many years must elapse before we can 
regard the period of Alpha Centauri as satisfactorily 
determined. 

Still, we have conclusive evidence in this case, 
as in that of the star 61 Cygni, that the component 
stars are really bodies of enormous weight, and con- 
sequently well fitted to sway the motions of families 
of planets. We conclude, therefore, that the fixed 
stars generally are suns, not mere lights; and, further, 
we are led to believe that there must be a general 
similarity in the conditions under which these bodies 
and our own sun emit light. And thus we are led 
to recognize other stars also — though as yet un- 
weighed — as massive orbs, not merely supplying light 



OTHER SUNS THAN OURS 255 

to other worlds travelling around them, but regu- 
lating by their attractive influences the orbital mo- 
tions of their dependent worlds. 

But we owe to the revelations of the spectro- 
scope the complete proof of these matters, besides 
evidence on other and equally interesting points. 

It had long been known that the spectra of the 
fixed stars present a general resemblance to the solar 
spectrum, though of course very much fainter, and 
that dark lines can be seen in these spectra, some 
of which correspond with those in the sun's spec- 
trum, while others seem to be new. So soon as the 
great discovery effected by Kirchhoff had been an- 
nounced, it was seen at once that these dark lines 
in the stellar spectra afford the means of determin- 
ing the constitution of the stars. It was only neces- 
sary that these lines should be identified by their 
correspondence with the lines belonging to known 
elements, in order to prove that these elements exist 
in the substance of the star. But, although the 
principle on which researches were to be conducted 
was sufficiently simple, many difficulties had to be 
encountered. Indeed, the attempts made by Airy, 
Secchi, and Eutherford, to solve the problem of de- 
termining the constitution of the stars by means of 
spectroscopic analysis, were unsuccessful; and it was 
not until Professor Miller and Mr. Huggins com- 
menced their famous series of researches that the 
problem can be said to have been fairly mastered. 

Even in the hands of these eminent physicists the 
work was difficult, and its progress tedious. The 



256 OTHER WORLDS THAN OURS 

weather necessary for the successful prosecution of 
so delicate a method of inquiry does not often pre- 
vail in our variable climate. The comparison be- 
tween the dark lines in the stellar spectra and the 
bright lines belonging to various elements was not 
only a delicate and laborious task, but was singu- 
larly painful to the eyes. And other difficulties, into 
which I have not space to enter here, had to be 
encountered and overcome. 

But, undeterred by these difficulties, the two 
physicists persevered in their researches, and were 
rewarded by results so interesting and important that 
their discovery may be said to constitute the most 
remarkable era in the history of sidereal research 
since the completion of the star-gaugings of the elder 
Herschel. 

Two bright stars, Betelgeux, the leading brilliant 
of Orion, and Aldebaran, the chief star of Taurus, 
were examined with special care. Mr. Huggins re- 
marks that the spectra of these stars are as rich in 
lines as the solar spectrum itself. The places of no 
less than eighty lines in the spectrum of Betelgeux 
were accurately measured, while as many as seventy 
lines had their places assigned to them in the spec- 
trum of Aldebaran. 

With respect to the former spectrum, Mr. Hug- 
gins remarks that it is most complex and remarkable. 
" Strong groups of lines are visible, especially in the 
red, the green, and the blue portions," a peculiar- 
ity, it may be remarked in passing, which serves to 
account for the well-marked orange-color of this star. 



OTHER SUNS THAN OURS 267 

Now, here already we have very decided evidence 
as to the nature of the star; since the very fact that 
its spectrum presents the same general appearance as 
the solar spectrum, proves conclusively that the star 
is an incandescent body, whose light comes to us 
through certain vapors corresponding to those which 
surround the sun. Nor should we be able to regard 
the star as other than a sun, even though none of 
the elements known to us should appear to be pres- 
ent in its substance, or in the vapors surrounding it. 
For, clearly, we have no reason for believing that 
worlds can be formed out of those elements only with 
which we are acquainted, unless we find, as we pro- 
ceed, that those elements actually do compose the 
suns which form the sidereal system. Of course, if 
this shall appear to be the case, our conclusions re- 
specting the nature of the stars will be very much 
strengthened. 

Now, when Professor Miller and Mr. Huggins 
compared the lines in the spectrum of Betelgeux with 
the bright lines of certain terrestrial elements, they 
found that some of these elements do actually exist 
in the vaporous envelope of the stars. Thus, sodium, 
magnesium, calcium, iron, and bismuth, are present 
in Betelgeux. The lines of hydrogen, which are so 
well marked in the solar spectrum, are not seen in 
the spectrum of Betelgeux. We are not to conclude 
from this that hydrogen does not exist in the com- 
position of the star. We know that certain parts of 
the solar disk, when examined with the spectroscope, 
do not at all times exhibit the hydrogen lines, or 



258 OTHER WORLDS THAN OURS 

may even present them as bright instead of dark 
lines. It may well be that in Betelgeux hydrogen 
exists under such conditions that the amount of light 
it sends forth is nearly equivalent to the amount it 
absorbs, in which case its characteristic lines would 
not be easily discernible. In fact, it is important to 
notice generally, that, while there can be no mis- 
taking the positive evidence afforded by the spectro- 
scope as to the existence of any element in sun or 
star, the negative evidence supplied by the absence 
of particular lines is not to be certainly relied upon. 

In the case of Aldebaran the two physicists were 
able to establish the existence of sodium, magne- 
sium, hydrogen, calcium, iron, bismuth, tellurium, 
antimony, and mercury, in the vapors surrounding 
the star. 

Besides these stars, fifty others were examined. 
The brilliant Sirius exhibits a spectrum of great 
beauty, though the low altitude which this star at- 
tains in our latitudes rendered the observation of the 
finer lines exceedingly difficult. But the two physi- 
cists were able to show that sodium, magnesium, hy- 
drogen, and probably iron, exist in this gigantic sun. 

All the stars examined exhibit spectra crossed by 
numerous lines; and, in a great number of the spec- 
tra, lines belonging to known terrestrial elements were 
detected. 

And now let us consider the general bearing of 
these interesting discoveries. 

In the first place, we are forced to recognize in 
the stars real suns, not mere lights. Doubtless Dr. 



OTHER SUNS THAN OURS 259 

Whewell did well in pointing out that astronomers 
had no right to regard the stars as suns, until they 
had some evidence that these orbs resemble the sun 
in other respects than in size, mass, or luminosity. 
And as in his day it appeared altogether unlikely 
that such evidence should be obtained, a real limit 
seemed placed to the speculations men might form 
as to the existence of other planetary systems be- 
sides those which circle around the sun. 

But now we have precisely that evidence which 
Whewell required. We see that the stars are con- 
stituted in the same general way as the sun, and 
that, further, they even contain elements identical 
with those which exist in his substance. There is 
not indeed in every case, perhaps there may not be 
in any case, an exact identity of composition between 
star and sun, or between star and star. But this 
was no more to have been looked for than an exact 
identity of physical habitudes among the members 
of the solar system. That general resemblance of 
structure which indicates a general resemblance in 
the purposes which the celestial bodies are intended 
to subserve, is undoubtedly evident, when we com- 
pare the stars either with our sun or with each other. 

I have already spoken of the conclusions to be 
drawn from the existence of the same materials in 
the substance of the sun that exist around ns on this 
earth. I have shown that we are compelled to regard 
this general resemblance of structure as sufficient to 
prove that the other planets resemble the earth, since 
we have no reason to believe that our earth bears 



260 OTHER WORLDS THAN OURS 

an exceptionally close resemblance to the sun as 
respects the elements of which she is composed. 

Since, then, we have reason to believe that all 
the planets which circle around the sun are con- 
stituted of the same materials which exist in his 
substance, though these materials are not necessarily 
nor probably combined in the same proportions 
throughout the solar system, we have every reason 
which analogy can give us for believing that the 
planets circling around Betelgeux or Aldebaran are 
constituted of the same materials which exist in the 
substance of their central luminary. 

Thus we are led to a number of interesting con- 
clusions even respecting orbs which no telescope that 
man can construct is likely to reveal to his scrutiny. 
The existence of such elements as sodium or calcium 
in those other worlds suggests the probable existence 
of the familiar compounds of these metals — soda, salt, 
lime, and so on. Again, the existence of iron and 
other metals of the same class carries our minds to 
the various useful purposes which these metals are 
made to subserve on the earth. We are at once in* 
vited to recognize that the orbs circling around those 
distant suns are not meant merely to be the abode of 
life, but that intelligent creatures, capable of apply- 
ing these metals to useful purposes, must exist in 
those worlds. We need not conclude, indeed, that 
at the present moment every one of those worlds 
is peopled with intelligent beings, because we have 
good reason for believing that throughout an enor- 
mous proportion of the time during which our earth 



OTHER SUNS THAN OURS 261 

has existed as a world no intelligent use has been 
made of the supplies of metal existing in her sub- 
stance. But that at some time or other those worlds 
have been or will be the abode of intelligent creat- 
ures seems to be a conclusion very fairly deducible 
from what we now know of their probable structure. 

But, secondly, apart from the information afforded 
by the spectroscope respecting the materials of which 
the stars are composed, the nature of the stellar spec- 
tra serves to prove most conclusively that the stars, 
besides supplying light to the worlds which circle 
around them, radiate heat also to them. Even if we 
were not certain that elements which are only vapor- 
ized at a very high temperature exist in the vaporous 
envelopes of the stars, yet the very nature of the 
light sent out by the stars indicates that these orbs 
are incandescent through intensity of heat. "When 
we find that the spectrum of a planet's light resem- 
bles the solar spectrum, we do not indeed conclude 
that the planet is as intensely heated as the sun, 
because we know that the planets are not self- 
ltiminous. But, in the case of self-luminous bodies 
like the stars, we can conclude from the very nature 
of their spectra that these orbs are intensely heated. 
Of course we are rendered absolutely certain of this 
when we find that iron and other metals exist in the 
form of vapor in the stellar atmospheres. 

The vast supplies of heat thus emitted by the 
stars not only suggest the conclusion that there must 
be worlds around these orbs for which those heat- 
supplies are intended, but point to the existence in 



262 OTHER WORLDS THAN OURS 

those worlds of the various forms of force into which 
heat may be transmuted. We know that the sun's 
heat poured upon our earth is stored up in vegetable 
and animal forms of life; is present in all the phe- 
nomena of Nature — in winds, and clouds, and rain, 
in thunder and lightning, storm and hail; and that 
even the works of man are performed by virtue of 
the solar heat-supplies. Thus the fact, that the stars 
send forth heat to the worlds which circle around 
them, suggests at once the thought that on those 
worlds there must exist vegetable and animal forma 
of life; that natural phenomena, such as we are 
familiar with as due to the solar heat, must be pro- 
duced in those worlds by the heat of their central 
sun; and that works such as those which man under* 
takes on earth — works in which intelligent creatures 
use Nature's powers to master Nature to their pur- 
poses — must go on in the worlds which circle around 
Aldebaran and Betelgeux, around Vega, Oapella, and 
the blazing Sirius. 

Eecently it has even been found possible to ren- 
der the stellar heat sensible to terrestrial observation, 
by methods which need not here be inquired into. 
Nay, the task of measuring the amount of heat re- 
ceived from certain stars has not been thought too 
difficult Mr. Stone, making use of the powers of 
the great equatorial of the Greenwich Observatory, 
and ingeniously overcoming the numerous difficulties 
which exist in a research of such exceeding delicacy, 
has arrived at the conclusion that Arcturus sends us 
about as much heat as would be received from a 



OTHER SUNS THAN OURS 263 

three-inch cube full of boiling water, and placed at 
a distance of three hundred and eighty-three yards. 
Vega, which shines, according to Sir J. Herschel, 
with about two-thirds the light of Arcturus, gives 
out about the same proportionate amount of heat. 1 
But in other instances the heat-giving power of a 
star has not been found proportional to the amount 
of light it emits. 

The variation of many fixed stars in lustre at 
once forms a new bond of association between the 
stars and the sun— which we have seen to be in real- 
ity a variable star — and suggests interesting inquiries 
as to the existence of variation in the emission of 
heat. Some of the stellar variations of light are so 
much more marked than those noticed in the case 
of our own sun that we can scarcely conceive how 
creatures, resembling any with which we are ac- 
quainted, could endure the effects of corresponding 
important variations of heat; nay, in some instances 



1 Although these results cannot yet be regarded as numerically exact, 
it may be interesting to consider the amount of heat giren out by Arcturus 
in relation to the light sent us by this star, the more so as this star seems 
(from the nature of its spectrum} to resemble the sun very closely in con- 
stitution. 

The light sent to us by Arcturus is equal to about three-fourths of 
that supplied by Alpha Centauri, or about 57000^00000^ P arfc °* ^ e ^^t we 
receive from the sun. Now, Mr. Stone estimates the direct heating effect 
of Arcturus at 0°. 00, 000, 127 Fahrenheit, making due allowance for the 
effect of the object-glass in concentrating and absorbing the heat. It will 
be seen at once that, according to this estimate, the heating power of 
Arcturus bears a very much greater proportion to that of the sun than 
the respective light-giving powers of these luminaries bear to each other. 
This seems to throw some doubt on the correctness of the estimate, either 
of the light-giving or of the heat-giving power of the star. 



264 OTHER WORLDS THAN OURS 

we seem compelled to withhold our belief in the 
existence of habitable systems around certain fixed 
stars. The star Eta Argus, for example, which some- 
times blazes out with a light surpassing that of any 
of the stars in the northern hemisphere, while at 
other times it falls to the sixth magnitude, can 
hardly be regarded as fit to be the centre of a 
system of worlds. I pass over such variable stars 
as the one which recently blazed out in the North- 
ern Crown, because in a case of this sort the star 
may be regarded as really a small orb, and its sud- 
den lustre as due to some exceptional occurrence, 
leading (as the spectrum of the star seemed to show) 
to a temporary conflagration. But Eta Argus and 
Mira Ceti seem to belong to a different category al- 
together, since it is probable as respects the former, 
and certain as respects the latter, that their appear- 
ance as stars of the leading magnitudes is not acci- 
dental, but part of a systematic series of changes. 

It remains only to be mentioned that, besides 
light and heat, the stars emit actinic rays. This is 
proved decisively by the fact that the stars can be 
made to photograph themselves. It has been found, 
however, that the actinic power of a star, like its 
heat-giving power, is not by any means proportional 
to the star's light So that in this respect, as in the 
material constitution of the stars, we find specific 
varieties even amid those very features which indi- 
cate most strikingly the general resemblance which 
exists between the suns constituting the sidereal 
system. 



OTHER SUNS THAN OURS 265 

To sum tip what we have learned so far from the 
study of the starry heavens — we see that, besides 
our sun, there are myriads of other suns in the im- 
mensity of space; that these suns are large and mas- 
sive bodies, capable of swaying by their attraction 
systems of worlds as important as those which circle 
around the sun; that these suns are formed of ele- 
ments similar to those which constitute our own sun, 
so that the worlds which circle round them may be 
regarded as in all probability similar in constitution 
to this earth; and that from those suns all the forms 
of force which we know to be necessary to the ex- 
istence of organized beings on our earth are abun- 
dantly emitted. Is it not reasonable to conclude that 
these suns have not been made in vain? If thought- 
ful men have reasoned rightly in supposing that the 
light and heat poured out by the sun upon the plan- 
ets which circle around him are not wasted — in the 
case of all the planets except our small earth — by 
being shed where no forms of life can profit by those 
abundant supplies, surely the argument is a million- 
fold stronger in the case of the fixed stars. Though 
here we cannot, as in the case of the solar system, 
actually see the worlds about which we speculate, yet 
the mind presents them clearly before us, various in 
size, various in structure, infinitely various in their 
physical condition and habitudes, but alike in this, 
that each is peopled by creatures perfectly adapted 
to the circumstances surrounding them, and that each 
exhibits, in the clearest and most striking manner, 

the wisdom and beneficence of the Almighty 
Science— 1 — 12 



CHAPTER XI 

OP MINOR STARS, AND OF THE DISTRIBUTION OP 
STARS IN SPACE 

IT has been so long a received opinion that a 
general uniformity of magnitude and distribu- 
tion characterizes the stellar system that it is 
with some diffidence I venture to express a different 
view. And here let me not be misunderstood. I 
am fully sensible that it is only in certain popular 
treatises of astronomy that a belief in anything like 
a real uniformity of structure in the sidereal system 
is attributed to astronomers of authority. It is not 
any such imaginary theory that I have now to deal 
with, however, but with opinions which have found 
a place in the works of astronomers from whom I 
very unwillingly differ. 

I propose to exhibit the reasons which have led 
me to believe that, so far from knowing the real 
figure of the sidereal system, astronomers have not 
been able to penetrate to its limits in any direction; 
that leading stars, such as those discussed in the pre- 
ceding chapter, are distributed throughout space to 
the very furthest limits and beyond the very furthest 
limits that our most powerful telescopes can attain to; 
(266) 



DISTRIBUTION OF STABS IN SPACE 267 

that the stars are arranged in groups and clustering 
aggregations, in streams and whorls and spirals, in a 
manner altogether too complex for us to hope to in- 
terpret; and that in these aggregations stars of all 
degrees of real magnitude are mixed up, from suns 
as large as Sirius down to orbs which may be smaller 
than any of the primary planets of the solar system. 

Now let us consider step by step the evidence we 
have on these points. 

We know, from the existence of double, triple, 
and multiple stars, in which the components are 
often very unequal in splendor, that combinations 
of stars exist in which one or two may be suns ri&e 
our own, while the rest, or some of the resi, are rel- 
atively minute. This, however, has of comse long 
been known; and it is only as a preliminary step in 
the investigation that I here advance so trite an 
instance. 

Next let us consider such star-clusters as contain 
orbs of the eighth or ninth magnitude, besides a 
multitude of minute stars. These clusters must of 
course be regarded as lying within the sidereal sys- 
tem, since no external galaxies could reasonably 
be supposed to contain orbs so infinitely transcend- 
ing even Sirius in magnitude as to shine, from be- 
yond the enormous gap separating us from such gal- 
axies, with a light exceeding that derived from many 
stars within the sidereal system. Now, regarding 
these clusters as forming part and parcel of the 
sidereal system, we find in the existence of multi- 
tudes of minute orbs within their range a proof that 



268 OTHER WORLDS THAN OURS 

diversity of magnitude in schemes of associated stars 
is to be regarded as a feature of certain parts, at any 
rate, of onr galaxy; and we shall therefore be the 
less surprised if we should find reason for believing 
that it is a characteristic peculiarity of the galactic 
system. 

Now, with regard to the nebulas (resolvable and 
irresolvable), and their claim to be regarded as ex- 
ternal galaxies, I shall have much to say further on; 
but I may remark, in passing, that we have precisely 
the same reasons for believing that many of these 
objects lie within the range of the solar system as 
have been already considered in the case of star- 
clusters. Their component stars, to be visible at all, 
must fall within the range of distance which astron- 
omers have assigned to the boundaries of the galaxy, 
since some stars even within that range cease to be 
separately visible in the most powerful telescopes 
man has yet constructed. So that when in these 
objects we see a few or many distinct stars, and a 
mass of nebulous light which we judge to proceed 
from an indefinitely large number of minute stars, 
we again have very decided evidence of the fact that 
in one and the same region of the sidereal system 
there may exist leading stars (so to speak) and in- 
numerable stars relatively minute. 

With considerations such as these (and I might 
add many others) to guide us, let us proceed to con- 
sider the teachings of the Milky Way itself, that we 
may see whether that wonderful zone indeed rep- 
resents, as has been thought, the sidereal system it- 



DISTRIBUTION OF STABS IN SPACE 269 

self, or only an aggregation of minute orbs altogether 
insignificant, separately, in comparison with our sun 
or Sirius, Aldebaran or Betelgeux, Vega or Arcturus. 
The star-gauging of Sir W. Herschel, interpreted 
according to his hypothesis of stellar distribution, 
pointed to an extension of the Milky Way laterally 
to a distance exceeding some eighty times that which 
separates us from the first-magnitude stars. So that, 
regarding sixth -magnitude stars as on the average 
about ten times as far from us as those of the first 
magnitude (the usual estimate), we see that the outer- 
most parts of the galaxy must lie (according to Sir 
W. Herschel' s theory) about eight times as far from 
us as the sphere of the sixth-magnitude stars. Now, 
Sir John Herschel was led by his observations of the 
southern heavens to so far modify his father's theory 
as to describe the Milky Way as probably shaped 
like a flat ring, the stars down to the tenth magni- 
tude being in a sense dissociated from the ring, 
while he regarded the probable distance of the outer- 
most limits of the ring as seven hundred and fifty 
times instead of but eighty times the mean distance 
of the first-magnitude stars. This difference of opin- 
ion, it may be remarked, though obviously not sur- 
prising when we consider the enormous difficulty of 
the problem presented by the sidereal system, is yet 
sufficient to indicate the probability that an impor- 
tant error has been made in the hypothesis which 
underlies the accepted theories respecting the galaxy. 
But, be this as it may, in regarding the Milky Way 
as shaped like a flat ring (cloven through one half of 



270 



OTHER WORLDS THAN OURS 



its circumference) whose medial section resembles 
generally the space between the dark concentric cir- 
cles in the accompanying figure (in which SB equals 
eight times SA), I have not adopted a structure 




Pig. 2.— The Galactic Cloven Flat Ring (plan). 

which exaggerates the difficulties presented by the 
disk or ring theory of the Milky Way. The cross- 
section would be somewhat as shown in Fig. 3. 

Now, accepting this modified figure, as better ac- 
cording with the results of star-gauging than Sir W. 




Fig. 3.— The Galactic Cloven Flat Ring (section). 

Herschel's theory that the Milky Way forms a cloven 
disk, let us consider whether any peculiarities of the 
Milky Way seem to oppose themselves to this inter- 
pretation of its structure. 



DISTRIBUTION OF STARS IIST SPACE 271 

In the first place, then, there is a gap or rift ex- 
tending right across the single part of the Milky 
Way in the constellation Argo; so that we must con- 
ceive that from S toward 1, in Fig. 2, the flat ring 
is broken through by some such rift as is indicated 
by the broken lines in that direction. Next there 
is, in the constellation Crux, a pear-shaped vacuity 
of considerable size, and bounded by well-defined 
edges; so that we must conceive that from S toward 
2 (Fig. 2) the flat ring is tunnelled through by some 
such passage as is indicated by the dotted lines in 
that direction. A similar tunnelling, but of different 
cross- section, must exist in direction S 3 (as shown 
by the dotted lines) to account for the dark gap in 
the constellation Oygnus. Next, where the Milky 
Way is double, a large portion of one branch is dis- 
continuous, so that the upper part of the double por- 
tion of the ring in Fig. 2 must be supposed removed 
between the broken lines from S to 4 and 5. Over 
the so-called double stream there are in places 
strange convolutions, in others numerous branching 
and interlacing streams, whose complexity indeed 
defies description; so that the portion 3 B 2 of the 
ring must be supposed corrugated in the strangest 
way, and further to throw out plane and curved sheets 
of stars presented tangentially toward S. Lastly, the 
single portion of the Milky Way is very faint indeed 
toward 6, so that here we must conceive its figure 
trenched in upon in the way indicated by the dot- 
and-peck line. 

Thus, even without considering a multitude of 



272 OTHER WORLDS THAN OURS 

minuter peculiarities of structure, we are led to the 
conclusion that the Milky Way, judged according to 
the fundamental hypothesis of Sir W. Herschel, has 
some such shape as I have endeavored to exhibit 
in the accompanying figure. Although I have not 
indicated here the corrugations of the ring, nor a 
tithe of the various overlapping layers which would 
be required to account for the appearance of the 
Milky Way between Centaurus and Ophiuchus, yet 
the deduced figure is by no means inviting in its 




Pig. 4.— The Galactic Flat Ring, modified in accordance with 
the observed peculiarities of the Milky Way. 

simplicity. It is, however, absolutely certain that 
the sidereal system, as far as its more densely aggre- 
gated star-regions are concerned, has some such fig- 
ure as this, if we are to accept the principle of Sir 
W. Herschers star-gaugings. 

Now, in turning our thoughts to the recognition 
of a more simple explanation of observed appear- 
ances, it will be well that we should consider some 
peculiarities of the Milky Way which we have not 
yet attended to. In the first place, I would invite 
attention to a peculiarity observed by Sir John Her- 



DISTRIBUTION OF STARS IN SPACE 273 

schei in different parts of the galaxy — the fact, 
namely, that in places the edge of the Milky Way 
is quite sharply denned. One half of a telescopic 
field of view may be quite clear of stars, or show 
only a few straggling orbs, while the other half pre- 
sents what has been called a "Milky Way field" — 
that is, a region profusely sprinkled with stars, the 
boundary between the two portions being well de- 
fined. When we see that a cluster of objects pre- 
sents a well-defined edge, what conclusion do we 
draw as to the position of the object? Is it not in 
such a case absolutely certain that the distance of the 
cluster enormously exceeds the distance between its 
component parts — or, in other words, that the ob- 
server is far outside the cluster? Many instances 
will at once suggest themselves to the reader in 
illustration of this remark. 

We conclude, then, that these portions of the 
Milky Way, at any rate, whether they be regarded 
as projections or nodules, are definite clustering 
aggregations very far removed from us. Other parts 
of the Milky Way may also be removed bodily, so 
to speak, to enormous distances, because a cluster 
which has not a definite edge may be as far removed 
as one which has; but certainly those portions are. 

Next let us consider what opinion we may found 
on the existence of dark regions in the Milky Way; 
and here I refer not merely to such large and obvi- 
ous vacuities as the coal-sack in Crux or the oval 
opening in Cygnus, but also to small openings, in 
which, though they occur even in rich regions of the 



274 OTHER WORLDS THAN OURS 

Milky Way, there is not, according to Sir W. Her- 
schel's description, even a telescopic star to be seen. 

Judged apart from preconceived opinions, such 
openings as these, according to all laws of proba- 
bility, indicate that the portion of the Milky Way 
in which they occur has not a very great lateral ex- 
tension. To return for a moment to Fig. 2, it will 
be seen at once that an aperture extending laterally 
through a star-system so shaped must have a par- 
ticular direction and be perfectly straight in order 
to be visible to observers placed, as we are sup- 
posed to be, in the central opening. It is altogether 
improbable that one such opening should exist by 
accident, and absolutely impossible that many 
should. 8 We are forced therefore to infer that, 
instead of the enormous lateral extension assigned 
to the Milky Way, the galaxy has in these places 
certainly, and elsewhere probably, a lateral extension 
not greatly exceeding its depth. 

It is further to be noted that the lucid stars over 
that zone of the heavens which is occupied by the 
galaxy show a very decided preference for the parts 
of that zone which are actually traversed by the 
Milky Way. For instance, we find no stars above 
the fifth magnitude, and very few of these, in the 
Coal-sacks, or in the rift which crosses the Milky 

1 Sir John Herschel has distinctly indicated this inference, as he has 
many other matters which make strongly against the received theory of 
the sidereal system. Nor is he unconscious of their bearing. Apparently 
unwilling at present to press them to their full extent, he is commonly 
satisfied by noting that they do not seem to accord with views he has 
elsewhere dwelt upon. 



DISTRIBUTION OF STARS IN SPACE 275 

Way in Argo, or, again, in the space which lies 
between the two branches where the Milky Way is 
double. If this is an accident, it is a very extraor- 
dinary one, especially when it is remembered that 
the region where it occurs is the very part of the 
heavens where stars of all magnitudes may be ex- 
pected to be most profusely distributed; that the 
spaces thus left vacant form no inconsiderable ali- 
quot part of that zone; and that, according to the 
accepted theory, there is no reason for expecting 
any peculiarity of the sort 

Thus, again, setting aside preconceived opinions, 
and judging only according to the evidence, we seem 
led to regard the coincidence as not accidental, but 
as indicating that there really is a very close asso- 
ciation between the bright stars and those small stars 
forming the milky light, which, according to the 
accepted theory, would lie so many times further 
from us. 1 

Now, if we have not been mistaken so far, it is 
very clear what views we are to form. If the Milky 
Way is to be, first, sl clustering aggregation separated 
from us by an interval comparatively clear of small 
stars; secondly, so shaped that the cross-section of the 
stream is everywhere not far from a roughly circular 
figure; and, thirdly, associated very closely with the 

1 I may add that, in drawing the maps for my new star-atlas, I have 
been very much surprised to find how in many cases the position, nay, 
the very shape, of the Milky "Way is indicated by the lucid stars which 
fall on its zone. Although my own views had led me to look for a 
peculiarity of the sort, it has been much more striking in its character 
than I had expected. 



276 



OTHER WORLDS THAN OURS 



bright stars seen in the same field of view, then must 
its structure be somewhat as shown in Fig. 5, iu 
which the disks represent lucid stars (very much 
exaggerated of course in size), while the fine dot- 
ting represents the spiral of relatively minute stars, 
clustering along the spiral group of leading stars. 
It will be seen at once how, to an observer placed 
at S, the various features of the Milky Way can be 




Fig. 5.— The Milky Way regarded as a Spiral. 

accounted for by this figure. Toward a would lie 
the gap in Argo; toward b two branches, one faint, 
and in part evanescent through enormity of distance, 
the other forming the brightest part of the spiral; 
toward d the projection in Cepheus; toward e the 
faint part of the Milky Way in Gemini and Mono- 
ceros. The Coal-sacks would be simply accounted 
for by conceiving that branches seen toward the 
same general direction, but at different distances, 
do not lie in the same general plane, and so may 
appear to interlace upon the heavens. We are not 
only justified in supposing this, but forced to do so 



A\v 



DISTRIBUTION OF STABS IN SPACE 277 

by the way in which the stream of milky light is 
observed to meander on its course athwart the heav- 
ens. The branching extensions serve very well to 
account for the appearance of the Milky Way be* 
tween Oentaurus and Ophiuchus, where the inter- 
lacing branches and the strange convolutions and 
clustering aggregations described by Sir John Her- 
schel are chiefly gathered. 

I would not have it understood, however, that I 
at all insist on the general shape of the spiral shown 
in Fig. 5. On the contrary, that curve is only one 
out of several which might fairly account for the 
observed appearance of the Milky Way; and I have 
often felt inclined to doubt whether a single spiral 
of this sort be in reality the best way of accounting 
for the observed appearance of the galactic zone* 
What I do insist upon as most obviously forced 
upon us by the evidence is, that (1) the apparent 
streams formed by the Milky Way upon the heavens 
indicate the existence of real streams in space; and 
(2) that the lucid stars seen on the stream are really 
associated with the telescopic stars which form, so to 
speak, the body of the stream. Whether that stream 
form a single spiral or several, or whether, instead 
of spirals, there may not be a number of closed rings of 
small stars, placed at different distances from us, and 
lying in all directions round the medial plane of the 
galaxy, but more or less tilted to that plane (the sun 
not lying within any one of the rings), are questions 
which can only be resolved by the systematic scrutiny 
of this wonderful zone. 



278 OTHER WORLDS THAN OURS 

The chief points to be noticed among the consid- 
erations flowing from these general views are these: 

In the first place, the only marked difference be- 
tween the stars of the leading magnitudes (say the 
first ten) lying in the galactic zone, and those lying 
without it, consists in the fact that the former are 
associated with countless multitudes of smaller stars, 
while the latter appear not to have such attendants, 
or not so many of them. We shall see presently that 
the extra-galactic stars are associated, and in a very 
intimate manner, with groups of very minute stars — 
of stars so minute indeed as not to be separately 
discernible — so that astronomers have been led to 
regard such groups as external galaxies. But, except 
in one region, we do not find outside the galactic 
zone any appearances reminding us of the aspect of 
the Milky Way itself. In that region lie the two 
Magellanic Clouds, resembling the Milky Way in 
their general appearance, but seen when placed under 
telescopic scrutiny to differ from it in this, that 
among the minute stars which cause the milky light 
are numbers of nebulae, of classes not found com- 
monly, if at all, in the galactic zone. 

In the second place, we must conclude that un- 
counted millions of stars exist which are very mi- 
nute indeed in comparison with those which we have 
been led to regard as suns. That these relatively 
minute orbs may be absolutely large — far larger, for 
instance, than our own earth — may indeed be ac- 
cepted as certain. But it is difficult to believe that 
they subserve purposes similar to those of our own 



DISTRIBUTION OF STABS IN SPACE 279 

sun. One cannot but see that orbs such as these 
would not have that permanence of character, as 
sources of heat-supply, which would seem to be nec- 
essary in the case of a real sun. We know, indeed, 
that among the small stars of the Milky Way there 
is a proneness to irregular variation which is not 
recognized, or is altogether exceptional, among the 
lucid stars. In the neighborhood of the Milky Way, 
with scarcely an exception, those temporary stars 
have blazed out which have formed a subject of such 
perplexity to the thoughtful astronomer. Under what 
conditions the small orbs in the Milky Way actually 
exist, whether clusters of them will eventually segre- 
gate from their neighbors to form suns, or whether^ 
after long voyaging in spiral and contorted paths 
under the varying influences of the attractions of 
leading stars, these minute orbs will, for the most 
part, be forced to settle down as attendants round 
the major ones, it is as yet altogether impossible to 
judge. It may be that they bear the same sort of 
relation to the leading stars that certain cometic and 
meteoric families, referred to in Chapter IX., bear 
to the major planets of the solar system, not being 
in any case absolutely dependent on any large star, 
but yet returning in cycles which must be measured 
by millions of eons, to temporary dependence on one 
sun after another, until in the course of time, under 
the action of processes somewhat resembling those 
I have conceived to take place in the formation of 
the solar system, the conditions under which they 
move will have become so far altered as to lead to 



280 OTHER WORLDS THAN OURS 

the breaking up of the Milky Way into distinct sys- 
tems. Indeed, as Sir William Herschel was led by 
other considerations long since to point out, there 
are signs in parts of the Milky Way which would 
seem to indicate that several such systems have 
already reached an advanced stage of development. 
But perhaps the most important conclusion de- 
ducible from the circumstances I have dwelt upon 
(assuming my interpretation of them to be in the 
main correct) is this, that we can no longer suppose 
we have in any direction pierced to the limits of the 
sidereal system. So long as a general approach to 
uniformity of distribution was understood to prevail 
within that system, there was a ready means of de- 
termining when the telescopist had reached in any 
given direction the limits of the system. To use the 
words of Professor Nichol, "When an eye is directed 
toward a prolonged bed of stars, there is no reason 
to fancy that it has reached the termination of that 
stratum so long as there appears, behind the lumina- 
ries which are individually seen, any milky or nebu- 
lous light; such light probably arising always from 
the blended rays of remoter masses. But, if, after 
struggling long with a nebulous ground, we obtain 
a telescope that gives us additional light with a per- 
fectly black sky, we then have every reason the cir- 
cumstances can furnish on behalf of the supposition 
that at length we have pierced through the stratum, 
a probability, indeed, which can be converted into 
certainty in only one way — viz., when no increase 
of orbs follows on the application of a still larger 



DISTRIBUTION OF STARS IN SPACE 281 

instrument." Sir John Herschel has expressed a 
similar view, and there can, indeed, be no doubt 
that, adopting the fundamental hypothesis on which 
accepted views are founded, the test above described 
is an absolutely certain one. 

But, if, instead of penetrating further and further 
into space when "struggling long with a nebulous 
ground" (to use Professor Nichols striking but some 
what incorrect expression), we have in reality only 
been searching with more and more minuteness within 
a definite cluster or stream of stars, we can no longer 
come to the conclusion he has insisted upon. We 
have reached the limits of minuteness which the stars 
of the cluster or stream attain to; we have learned 
perhaps all that we can learn about that cluster or 
stream; but we can no more be said to have reached 
the limits of the sidereal system in that direction than 
we can be said to have reached the outermost bounds 
of the universe in the direction of the cluster in Her- 
cules, when that magnificent object has been thor- 
oughly resolved with the telescope. 

Here, then, if I have seemed to narrow the limits 
of the sidereal scheme by bringing the star-myriads 
of the Milky Way, which had been regarded as many 
times further from us than the lucid stars, into direct 
association with these luminaries, I make amends by 
pointing out that in all probability the limits of the 
sidereal system lie far beyond the range of the most 
powerful telescopes man has yet constructed. In 
fact, there is here a somewhat singular interchange 
of position between the new and the accepted theo- 



282 OTHER WORLDS THAN OURS 

Ties. According to the views usually accepted, the 
small stars in the Milky Way are really as large, on 
the average, as the lucid stars, whereas, according 
to my views, they are relatively minute. But, accord- 
ing to the accepted theories, the scattered stars of 
very low magnitudes in the extra-galactic heavens 
must be regarded as relatively minute, since it has 
been rendered certain, according to those theories, 
that the limits of the sidereal system are relatively 
close in this direction, and we cannot suppose these 
stars to lie beyond those limits (as they must do, if 
really large). Now, according to my views, there is 
nothing to prevent these minute stars from including 
among their number orbs as vast as Sirius, or many 
times vaster. Nay, even within the galactic zone 
itself there are stars to which my theory gives as 
noble proportions as the accepted views. For, in 
the southern Coal-sack, there are minute telescopic 
stars, as Sir John Herschel tells us, and these orbs, 
according to the accepted views, must be regarded 
as belonging to the galactic circle, though inexpli- 
cably segregated from their fellows. According to 
the views I have been led to form, many of these 
telescopic stars must be regarded as suns lying far 
beyond the galactic spiral, or perhaps associated with 
outer whorls of this spiral which no telescope made 
by man can ever reveal to us. 

And this leads me to consider two phenomena 
which are altogether inexplicable, I conceive, on any 
theory except mine. 

The first is the existence of excessively faint 



DISTRIBUTION OF STARS IN SPACE 283 

Streams of light— star-streams doubtless, though the 
components are not separately visible — in certain 
regions of the heavens. Sir John Herschel, who 
detected this strange phenomenon, speaks of the 
streams as so very faint that the idea of illusion has 
continually arisen subsequently; yet he dwells far 
too clearly on the characteristics of the phenomenon 
for any doubt to remain as to its reality. The faint- 
est possible stippling of the field of view — the minute 
points of light being obviously there, though it was 
impossible to see them individually — a mottling which 
moved with the stars as he moved the tube to and 
fro, such are the terms in which Sir John Herschel 
speaks of this interesting phenomenon. 

Now, no doubt whatever can exist that, if these 
faint streams really belong to the sidereal system, 
they are left altogether unaccounted for by the or- 
dinary views respecting the structure of that system. 
There is no continuity between the stars composing 
them and even the minutest telescopic stars visible in 
the same general direction; so that a vast void must 
separate them from the outermost of those telescopic 
stars. According to my theory, they simply belong 
to outlying whorls of the spiral galaxy, and the tele- 
scopic stars seen upon them bear the same relation 
to them that the lucid stars bear to the Milky "Way. 

The second point is perhaps even more striking. 
In certain directions Sir John Herschel recognized 
the existence of two or more distinctly-marked classes 
of stars, as though, he says, definite sets of stars, 
separated by comparatively void intervals, lay in 



284 OTHER WORLDS THAN OURS 

those directions. It is clear that this association of 
the stars into sets is as distinctly opposed to the 
views ordinarily accepted as it is obviously an ar- 
rangement to be expected according to my theory 
of the constitution of the sidereal system. 

Quite early in my consideration of the subject I 
am now upon, the idea suggested itself to me that 
in the proper motions of the stars we have a means 
of forming an estimate of the distances of these orbs; 
and, further, of detecting any laws associating them 
together, whether into streams or clusters; and that 
the evidence thus obtained was likely to be in many 
respects more trustworthy than that afforded by the 
apparent magnitudes of the stars. Two processes of 
inquiry suggested themselves. The first consisted in 
a careful comparison of the mean motions of stars 
of different apparent size, in order to determine 
whether, on the average, small stars are so far off 
that we can look upon them as in reality no smaller 
on the average than those which appear larger. The 
second consisted in charting down the proper mo- 
tions, so as to detect any signs of star-drift which 
might haply appear in different parts of the heavens. 
1 confess that I had not by any means expected 
results so strikingly confirmatory of my views as 
those I actually obtained. 

The first method of inquiry, instead of giving an 
average amount of proper motion to the smaller stars 
somewhat, or perhaps even considerably, greater than 
was to be expected, according to the theory which 
sets these stars at an enormous distance, actually 



DISTRIBUTION OF STARS IN SPACE 285 

gave them a mean motion equal to that of stars of 
the first three magnitudes. It became evident, then, 
that not only are small stars (I am here speaking of 
stars visible to the naked eye) mixed up as I had 
thought with bright stars visible in the same general 
direction, but that distance is less available to ex- 
plain the smallness of the stars even than I had 
supposed. I had thought that certainly a large pro- 
portion of the small stars must in reality be very far 
from us; but it appeared that the proportion of stars 
whose smallness is so to be accounted for is in real- 
ity exceedingly minute. There must therefore be 
myriads of really small stars for every leading orb. 
The second method of research led to the strange 
result that in many parts of the heavens a commu- 
nity of motion can be recognized, among star-groups 
far larger in extent than I had expected to find thus 
drifting through space. Knowing that, whatever view 
we form of the sidereal universe, we must yet recog- 
nize the fact that in every direction stars at very 
different distances must be visible, I had not hoped 
to find over any large region of space the traces of a 
community of motion. Nor even in small regions 
had I hoped to recognize very decided traces of star- 
drift, because I was conscious that, even with three 
or four stars really forming a drifting group, there 
would nearly always be found three or four others, 
either much further off or much nearer, and alto- 
gether dissociated from the drifting set. Indeed, I 
imagined, when I began the inquiry, that the most 
remarkable instance of star- drift in the heavens was 



286 



OTHER WORLDS THAN OURS 



that detected (though differently explained) by Baron 
Madler in the constellation Taurus. 

I found, however, that in other regions a far more 
obvious tendency to drift can be recognized. Per- 
haps the most remarkable instance of all is that illus- 



•ji 



jr y 




trated in the accompanying plate. This picture rep- 
resents the motions in the constellations Cancer and 
Gemini. It will be noticed that though here and 
there stars apparently not belonging to the system 
appear in the same range of view, yet the star-drift 



DISTRIBUTION OF STARS IN SPACE 287 

is unmistakable. The general parallelism of motion 
is very striking; and the difference in the amount of 
motion observed in different stars is only what was 
to be expected in a star-group whose range in dis- 
tance, if equivalent to its lateral extent, must be such 
as fully to account for the range in the amount of 
apparent motion. 

Fig. 6 exhibits one out of many parts of the 



C-: - 


•■»•»«, 

»«.«?**" 








y 



Fig. 6.— Observed Proper Motions of Stars in Ursa Major and Neighborhood. 

heavens in which different sets of stars are observed 
to be drifting in different ways. 

It will be seen that here there are three sets — 
those included in the space a, those in space 5, and 
those left unenclosed, which are very obviously drift- 
ing, each in its special direction. The stars within 
the space b are /?, p, o\ e, and C, of the Greater Bear, 
with three smaller stars. Their drift is, I think, most 



288 OTHER WORLDS THAN OURS 

significant. If in truth the parallelism and equality 
of motion are to be regarded as accidental, the coin- 
cidence is one of a most remarkable character. But 
such an interpretation can hardly be looked upon as 
admissible, when we remember that the peculiarity is 
only one of a series of instances, some of which are 
scarcely less striking. One of these is presented in 
the accompanying figure in which the proper motions 
in the stars a, /?, and p, Arietis, and four other stars 
in the neighborhood, are exhibited. 1 

Here p and y may be regarded as drifting with a, 

06 



S Ky 



Fig. 7.— Observed Proper Motions of Stars in Head of Aries. 

but having a motion of their own in addition, suf- 
ficing to account for the want of strict parallelism 
between their apparent motion and that of a. The 
other stars seem obviously to belong to the same 
system. 

I am led, by the facts which have here been 
briefly considered, rather to urge those who have 
time and inclination to inquire carefully into the 
minuter details of the sidereal heavens than to- in- 

1 In all these figures the proper motion indicated by the length of the 
arrow attached to a star corresponds to the star's motion in thirty-six 
thousand years. 



DISTRIBUTION OF STARS IN SPACE 289 

sist on any views of my own. "While I recognize 
the wisdom and necessity of that course which the 
Herschels adopted in taking a wide view of the side- 
real system, and in dealing rather with general re- 
sults than with special peculiarities, I think the time 
has come when another course is possible and advis- 
able. The Herschels having surveyed the field of 
heaven, it behooves us now to go over it with a 
close and searching scrutiny. To consider averages 
now is to level the scarcely perceptible undulations 
in our field of research, as well as its better-marked 
ridges or depressions; whereas we require, on the 
contrary, to exaggerate the variations of level, so 
that we may determine with more certainty what are 
the peculiarities presented by that most interesting 
field to man's contemplation. Or, to change the 
illustration, and to quote the words of the greatest 
living master of that kind of research which 1 have 
been advocating, "We must not be deterred from 
dwelling consecutively and closely on these specu- 
lative views by any idea of their hopelessness which 
the objectors against * paper astronomy' may enter- 
tain, or by the real slenderness of the material 
threads out of which any connected theory of the 
universe has (at present) to be woven. 'Hypotheses 
fingo' in this stage of our knowledge is quite as good 
a motto as Newton's 'Non jingo* — provided always 
they be not hypotheses as to modes of physical 
action for which experience gives no warrant. ' ' ■ 

1 From a letter addressed by Sir J. Herschel to the present writer, 
August 1, 1869. 
Science — 1 — 13 



CHAPTEE XII 



THE NEBULAS: ARE THEY EXTERNAL GALAXIES? 



IN" the last chapter I have indicated reasons for 
believing that the sidereal system extends far 
beyond the range of the most powerful tele- 
scopes man has yet been able to construct. It need 
hardly be said that, supposing this view to be cor- 
rect, we cannot possibly see any external galaxies, 
unless they surpass our own many thousands of times 
in richness and splendor. Every analogy that we 
have for our guidance points to the conclusion that, 
if our galaxy have limits, and there exist in space 
other galaxies, then those outer systems must be sep- 
arated from ours by spaces exceeding the dimensions 
of the several galaxies many thousand or many mil- 
lion fold in extent. We know that the distances 
separating the satellites from their primaries exceed 
in an enormous ratio the dimensions of the satellites. 
The distances separating the planets from each other 
exceed in an enormous ratio the dimensions of the 
planets. The distances separating our solar system 
from others enormously exceed the dimensions of the 
various solar systems. And we may conclude that in 
all probability the distances separating our sidereal 
(290) 



THE NEBULA 291 

system from other similar systems in space must ex- 
ceed in an enormous ratio the dimensions of our 
galaxy, and of all other such systems. 

That the sidereal system has limits I do not 
doubt. Of course it may be coextensive with space 
that is absolutely infinite in extent; but we have no 
reason for believing that, in rising step by step, from 
system to system, until we have reached the highest 
class of system known to us, we have reached the 
real summit of that perhaps altogether limitless range 
of steps. We know, indeed, that if light do not 
suffer extinction in traversing space (and we have 
as yet no evidence that it does), the extent of the 
sidereal system must be limited, since otherwise the 
whole of the starlit sky should shine with the bril- 
liancy of sunlight. 1 And we may carry this argu- 

1 This is, perhaps, obvious; but, if not, the following proof may be 
accepted : Let the whole of space be conceived divided into spherical shells, 
having our earth at their centre, the thickness of each shell being r. Then 
taking two shells, one at a distance r, the other at a distance / (both r and 
v* much greater than »), we see that the number of stars in these shells 
will be proportional to r* * and r* t respectively ; that is, will be indepen- 
dent of the thickness of the shell and vary as the square of its radius. 
(Here I am not concerned with those departures from uniformity which I 
have considered in the last chapter, because I suppose each shell large 
enough to include within it all varieties of distribution and aggregation. 
This applies, also, to what follows.) Now, the average apparent size of 
the stars of one shell will be to the average apparent size of stars in the 
other in the inverse proportion of the respective radii of the shells, the in- 
trinsic brightness of the light received from the stars of each set being 
equal. Thus the total amount of light from the stars of one shell is to the 

total amount of light from stars in the other, as r 2 r x -r : r' 8 r x -75 1:1. 
Hence, supposing the amount of light received from one shell to be -th 

K 

part of that which would be received if the whole celestial sphere were as 



292 OTHER WORLDS THAN OURS 

ment even further. For, though the sidereal system 
should be limited, but other systems similar to it 
spread throughout the infinity of space, there would 
still result this ineffable blaze of light, surpassing the 
light of day as greatly as the vault of heaven sur- 
passes the disk of the sun. And this again would be 
true, though this system of systems were limited in 
extent, but surrounded by similar systems of systems 
in the infinity of space. And so on, let the order of 
systems which finally becomes infinite in number be 
what it may. There is only one way to escape from 
this limitless series of system-orders — that is, by 
accepting as true the hypothesis that light suffers 
extinction as it voyages through space. But it is 
worth noticing, when we are actually dealing with 
the infinity of space, and when, therefore, limitless 
conceptions are not paradoxical, but in reality as 
available for our purposes as finite conceptions would 
be, that if we do adopt the belief in an infinite suc- 
cession of orders of systems, that is, first satellite- 
systems, then planetary -systems, then star-systems, 

bright as the sun's, that is as a star's disk — k being inconceivably large, 

1 
the amount received from the other is also -th of this amount, and the total 

k 

from all the shells must, therefore, be - -j hrH to infinity. 

fC rC tC fC 

Now, by taking k terms of this series (or k shells out of our infinite series 
of shells), we should get unity, that is, the whole heavens lighted up with 
starlight or sunlight. There would be a proportion of stars in the same 
visual line and so hiding each other ; but, since we can take 2 k, 3 k, or 
infinity times k if need be, there can be no doubt the whole heavens would 
be lighted up with solar brightness. 



THE NEBUL& 293 

then systems of star-systems, then systems of systems 
of star- systems, and so on to infinity, and if we 
accept as true of this infinite series what we know 
to be true of the part within our ken, viz., that the 
distance between the components forming any system 
is indefinitely great compared with the dimensions of 
those components, we no longer have as a conclusion 
that the whole heavens should be lighted up with 
stellar (that is with solar) splendor; even though, in 
this view of the subject, there are in reality an in- 
finite number of stars, just as in the view according 
to which the sidereal system extends without inter- 
ruption to infinity. 1 



1 It is clear that we no longer get, as in the previous note, a series of 

equal small terms. If we take our infinite series of shells as before, we get 

1 » 

for the sidereal system n times - where « is finite and therefore finite. 

n 
We must indeed assume - to be small, and so of other similar ratios pres- 

tC 

ently to be dealt with. With respect to the system of systems we hare 
these considerations to guide us — any of the spherical shells within this 
system must supply to our skies an amount of light indefinitely less than 

one of the shells within the sidereal system itself, say r,th part only, # in- 
definitely large ; but the number of shells falling within that system is very 
much greater, say n' times as great where »' is finite. Therefore we get for 
the total amount of light coming from the system of systems a quantity 

nn' 
proportional to -rp» and so for the system of system of systems we get a 

nn' n" 
quantity proportional to ■ > where W is indefinitely large, n" very 

jg 
large. And for each successive order we get a multiplier of the form , 

where K is indefinitely large and s very large indeed. Suppose - to be the 

m 



294 OTHER WORLDS THAN OURS 

But whether we adopt this or any other view of 
the way in which external systems are arranged, this 



n ( v v 2 



largest of all these multipliers, then the total amount of light received 
from the infinite system of systems is proportional to less than 

■4 .... to infinity J, 

n ( K \ 
(in which v is supposed to be less than k, i.e., to less than - ( J, a 

Suite quantity, which will even be minute if k and « are severally much 
greater than n and v. 

This particular mode of escaping from the difficulty suggested by the 
ifliimination of the heavens, without adopting the theory that light suffers 
extinction in its passage through space, occurred to me while I was pre- 
paring a series of papers entitled "A New Theory of the Universe," which 
appeared in "The Student" in the spring of 1869, and I there exhibit the 
considerations just dealt with. I was much pleased to find, from a letter 
of Sir John Herschel's, that the same idea had suggested itself to him ; as 
I was thus encouraged to believe that I had not gone very far astray in the 
whole series of papers, whereof the matter in question had seemed to me 
the most speculative portion. The following are the words in which Sir 
John Herschel, writing in ignorance of my having adopted the same view, 
expresses the ideas above dealt with: "One of the arguments advanced in 
favor of the spatial extinction of light was that, if there is not such extinc- 
tion, the whole heavens ought to be one blaze of solar light — admitting 
the universe to be infinite, because it was contended that there could then 
be no direction in space in which the visual ray would not encounter a star 
(i.e., a sun). This argument is fallacious, for it is easy to imagine a con- 
stitution of a universe literally infinite which would allow of any amount 
of such directions of penetration as not to encounter a star. Granting that 
it consists of systems subdivided according to the law that every higher 
order of bodies in it should be immensely more distant from the centre than 
those of the next inferior order — this would happen. Thus, in our own, 
the moon is very near the earth, the satellites to their primaries. These 
primaries are immensely more distant from the sun, their centre ; the fixed 
stars again still more immensely more remote from the sun. Suppose our 
system to terminate with the visible fixed stars ; then imagine a system of 
such systems as remote from each other, in comparison with their own 
dimensions, as the distance of the fixed stars in comparison with the plane- 
tary system ; such systems seen from each other would subtend no greater 
angle than a star seen from the sun — and so on." 



THE NEBULA 295 

at any rate is certain, that if the stars at the outer 
parts of our own sidereal system be beyond the ken 
of our most powerful instruments — and I have shown 
that there are strong reasons for this conclusion — 
then the component suns of external galaxies cannot 
by any possibility be visible. So that, according to 
this view, all resolvable nebulae, at least, must be 
dismissed from the category of external galaxies. 
Nor will it be thought probable that irresolvable 
nebulae are external galaxies, if once that view of the 
extent of the sidereal system is adopted. 

But there are independent considerations, on which 
I prefer now to dwell, for believing that all the 
nebulae belong to the sidereal system. 

It will hardly be necessary, let me remark in 
passing, for me to point out how this matter is 
associated with the subject of other worlds. It is 
true that, when once it is admitted that there are 
external galaxies, it may be looked on as a matter 
of small importance (so far as the subject of this 
treatise is concerned) whether we can actually see 
those galaxies or not. I am not, for instance, in 
the same position as Dr. Whewell, who assigned to 
the nebulae what I take to be their true place in the 
universe, with the express object of overthrowing 
the belief that there exist other galaxies as vast as 
the sidereal or vaster, thronged with suns which are 
severally the centres of planetary systems, within 
which again are worlds as well suited to be the 
abode of life as this earth on which we dwell. But, 
though my purpose is different from his, it is equally 



296 OTHER WORLDS THAN OURS 

necessary that I should insist on the true position of 
the nebulae. Because, if these objects form indeed 
part of the sidereal system, the relations they present 
are of extreme importance. They exhibit to us 
within the bounds of our galaxy systems altogether 
different from the solar system, and thus suggest 
ideas of other classes of worlds peopled with their 
own peculiar forms of life, as distinct, perchance, 
even in their general characteristics, from any found 
amid the systems circling round stars, as the forms 
of life in Venus or in Mars must be in their special 
characteristics from those existing on our own earth. 

Freed from those analogies which led the elder 
Herschel to regard the stellar nebulae — resolvable and 
irresolvable 1 — as external star-systems, let us consider 
the relations presented by these and other nebulae, 
without reference to preconceived opinions. 

We must first pay attention to one of the most 
striking of the discoveries which the spectroscope has 
yet enabled man to make — the discovery that certain 
nebulae are gaseous. It is necessary to consider this 
significant discovery, rather than those which were 
the first to exhibit the real place of the nebulae in 
our scheme, because we shall thus be able to divide 
the nebulae at once into two great classes, instead of 
being led to this arrangement by following out the 
history of those long processes of research by which 



1 By irresolvable Btellar nebulae, I mean those nebulae which, though 
not resolvable into stars, yet present the characteristic features which lead 
astronomers to believe that only increase of telescopic power is needed in 
order to effect resolution. 



THE NEBULJE 297 

the two great orders of nebulae were long since sep- 
arated from each other under the piercing scrutiny 
of Sir William Herschel. 

The reader will see how the spectroscope could at 
once resolve a question which ordinary observations 
would be all but powerless to deal with. The neb- 
ulae being self-luminous, the nature of the matter 
which is the source of their light would be shown 
by the character of the spectrum, as distinctly as 
though that matter were actually present in the 
laboratory of the spectroscopist. 

Mr. Huggins thus describes the observation which 
first revealed the true nature of certain orders of the 
nebulae. The object under examination was a neb- 
ula in Draco, belonging to the class of planetary 
nebulae: "On August 19, 1864, I directed the tele- 
scope, armed with the spectrum apparatus, to this 
nebula. At first I suspected some derangement of 
the instrument had taken place, for no spectrum was 
seen, but only a short line of light perpendicular to 
the direction of dispersion (that is, to what would in 
the case of solar light be the length of the spectrum). 
I then found that the light of this nebula, unlike any 
other ex- terrestrial light which had yet been sub- 
jected by me to prismatic analysis, was not composed 
of light of different refrangibilities, and therefore 
could not form a spectrum. A great part of the 
light from this nebula is monochromatic, and after 
passing through the prisms remains concentrated in 
a bright line, occupying the position of that part of 
the spectrum to which its light corresponds in re- 



■■■ 



298 OTHER WORLDS THAN OURS 

frangibility. A more careful examination f however, 
showed that — a little more refrangible than the bright 
line, and separated from it by a dark interval — a nar- 
rower and much fainter line occurs. Beyond this 
again, at about three times the distance of the sec- 
ond line, a third exceedingly faint line was seen. 
The positions of these lines in the spectrum were 
determined by a simultaneous comparison of them in 
the instrument, with the spectrum of the induction- 
spark taken between electrodes of magnesium. The 
strongest line coincides in position with the brightest 
of the air-lines. This line is due to nitrogen. . . . 
The faintest of the lines of the nebula agrees in posi- 
tion with a line of hydrogen. The other bright line 
was not found to correspond with a known line of 
any terrestrial element. Besides the bright lines, an 
exceedingly faint spectrum was just perceived for a 
short distance on both sides of the group of bright 
lines. " Mr. Huggins suspected that this was not uni- 
form, but crossed with dark spaces. Subsequent ob- 
servations on other nebulsB 1 induced him "to regard 



1 One of the most interesting of Mr. Huggins' researches into the sub- 
ject of the light of nebulas is his attempt to determine its intrinsic bril- 
liancy. By comparing the light of certain gaseous nebulae with that of a 
sperm-candle (of the size called six to the pound), he found that these 
objects, assumed to be continuous, shine with a light varying in intrinsic 
brilliancy from the 1,500th to the 20,000th of that of such a candle. By 
a strange misconception, Mr. Lockyer, in discussing Mr. Huggins* result, 
speaks of the comparison as though it related to the absolute brightness 
of the nebulas, saying that "such a candle a quarter of a mile off is 20,000 
times more brilliant than the nebula." Mr. Huggins 1 result is wholly 
distinct from this, and much more important. His comparison relates to 
the intrinsic luminosity of the nebular substance, not to the quantity of 



THE NEBULJE 299 

this faint spectrum as due to the solid or liquid mat- 
ter of the nucleus, and as quite distinct from the 
bright lines into which nearly the whole of the light 
from the nebula is concentrated." 

Thus was solved a problem which had, for the 
best part of a century, perplexed astronomers. There 
was not, indeed, a full answer to all the questions of 
interest associated with the problem. But it had 
been laid down by Sir "William Herschel, as a legit- 
imate conclusion from observation, that certain orders 
of the nebulae are gaseous, and astronomers had 
ranged themselves for and against this proposition. 
Telescopic improvements had seemed at length to 
turn the scale in favor of those who held Sir Wil- 
liam Herschel to have been mistaken. Already the 
problem had seemed all but definitively settled: and 
then in a moment this observation by Mr. Huggins 
had reversed the whole matter. It was now estab- 
lished, beyond all possibility of future question, that, 
on the main point, the greatest of modern astrono- 
mers had been altogether in the right. 

The orders of nebulae which give a spectrum of 
bright lines would seem from Mr. Huggins' obser- 
vations to be (1) the planetary nebulae, (2) the ring 
nebulae, (3) the irregular nebulae. The spiral nebulae 
seem, for the most part, to give a continuous spec- 
trum, but some of these objects give the bright-line 
spectrum indicative of gaseity. The orders of nebulae 

light received from the nebulae. (The distance of the candle in Mr. Hug- 
gins' observations is no* considered in the result; it was a mere matter of 
convenience.) 



300 



OTHER WORLDS THAN OURS 



which give a continuous spectrum appear to be the 
following: (1) star groups, (2) clusters, regular and 
irregular, and (3) easily resolvable nebulae. Of the 
irresolvable nebulas a large proportion seem to be 
gaseous. 1 

Here, then, we find the nebulas ranged into two 
important divisions, apparently separated by a dis- 
tinct line of demarcation. Yet one is tempted to 
inquire whether these divisions may not in reality 
run into each other, by the fact that among nebulas 
of certain orders are objects belonging to both divis- 
ions. And the fact that, beneath the bright-line 
spectrum of the gaseous nebulae, a faint continuous 
spectrum may be seen, seems also to point in the 
same direction. We know that, so far as the tele- 
scopic appearance of the nebulas is concerned, there 
is very striking evidence of a gradual progression 
from clusters to irresolvable nebulas, and, therefore, 



1 The following classification of nebulae in this respect, by Lord Qxman- 

town, is interesting as indicating the results of observations made with so 

powerful an instrument as the great Parsonstown telescope (the six-foot 

reflector): 

Continuous Gaseous 
Spectrum. Spectrum. 

Clusters 10 



Certainly or probably resolved ? 
Certainly or probably resolvable ? 
Blue, or green, no resolvability . 
No resolvability detected . 



5 

10 





Total observed 



31 



15 



Adding nebulas not observed at Parsonstown, there are in all 41 which 
exhibited a continuous spectrum, and 19 which gave a spectrum indicative 
of gaseity. 



^ 



THE NEBULA 801 

we are led to inquire, whether the spectroscope con- 
veys a similar lesson. 

Now, this question could only be answered satis- 
factorily by the observation of a series of nebulae 
having spectra progressively varying, from bright 
lines on an almost invisible continuous spectrum 
to a continuous spectrum with the same bright lines 
superposed on it, but almost imperceptible, because 
their brightness so little exceeded that of the con- 
tinuous spectrum. We have not evidence of such 
completeness. But Lieutenant Herschel has observed 
in the southern heavens a clustering nebula with a 
continuous spectrum, on which he could just detect 
the three bright lines seen in the spectra of the gase- 
ous nebulae. And, so far as this evidence extends, 
the conclusion is obvious, that the various orders of 
nebulae are orders of but a single family. It will be 
seen presently that this conclusion, which is strik- 
ingly corroborated by other evidence, has a very im- 
portant bearing on the views we are to form respect- 
ing the relations between the nebulae and the sidereal 
system. 

The first process by which we must attempt to 
form a correct estimate of the nebular system cor- 
responds to Sir William Herschel's process of star- 
gauging. We must inquire according to what general 
laws the nebulae are spread over the vault of heaven. 

Now, when this is done, it appears that there is 
a well-marked peculiarity in the arrangement of the 
nebulae, a peculiarity as striking as the existence of 
the galactic circle itself. The nebula seem to with- 



ff 



302 OTHER WORLDS THAN OURS 

draw themselves from the neighborhood of the galaxy. 
In the northern heavens they cluster very definitely 
toward the pole of the galaxy; in the southern they 
are arranged in streams and clustering aggregations, 
but the galaxy itself is, in either case, left almost 
clear of nebulae. 

If this peculiarity is accidental, the coincidence 
involved is most remarkable. Had there been a zone 
of nebulae, and that zone had shown a tendency to 
coincidence with the Milky Way, the relation would 
have been held strikingly indicative of a real associ- 
ation between the nebular and the sidereal systems. 
But is the direct converse of this relation more 
likely to be the effect of chance? Have not observ- 
ers and experimenters concluded (in every other sim- 
ilar instance) that a law , of contrast is as indicative 
of a real connection as a law of association ? It is 
surprising, therefore, that nearly all astronomers, who 
have considered the relation in question, have re- 
garded it as affording strong evidence that the neb- 
ular system is wholly dissociated from the sidereal. 

Next let us turn to special features. In the first 
place, let us inquire whether the different orders of 
nebulae exhibit any peculiarities of arrangement. 

We find that clusters exhibit a very marked pref- 
erence for the neighborhood of the Milky Way; re- 
solvable nebulae seem to prefer the galactic zone, but 
not in so decided a manner; and it is only among 
the irresolvable nebulae that we recognize that with- 
drawal from the Milky Way which had seemed char- 
acteristic of the whole nebular system, before we 



THE NEBULA 808 

considered its several orders. The fact that the 
irresolvable nebulae form about four-fifths of the 
total number will account for the circumstance that 
a peculiarity really appertaining to that order alone 
should appear to belong to the whole system of 
nebulae. 

Again, the planetary and irregular nebulae are 
found to affect the neighborhood of the Milky Way. 
I have already mentioned that these objects are 
gaseous. 

It is easy to see what general conclusions may be 
deduced from the peculiarities here touched upon. 
Obviously the first shows us most distinctly that 
there is a relation between propinquity to the Milky 
Way and the character of nebulae as respects resolv- 
ability — a relation which points in the most decisive 
manner to the existence of a close association be- 
tween the sidereal system, of which the Milky Way 
certainly forms part, and the nebular system, from 
which clusters and resolvable nebulae cannot reason- 
ably be separated. It is equally obvious that the 
second peculiarity indicates the existence of a close 
association between the Milky Way and the charac- 
ter of the nebulae as respects gaseity; a relation 
which brings all the gaseous nebulae into close asso- 
ciation with the sidereal system, since we know that 
among the extra-galactic nebulae there are many 
which are principally formed of the very same 
gases which appear in the irregular and planetary 
nebulae. When we consider that those peculiarities 
of configuration and of constitution which have alike 






mr* 



304 OTHER WORLDS THAN OURS 

seemed to indicate that the various orders of nebulas 
merge into each other by indefinable gradations are 
both associated, in a very distinct manner, with the 
most marked peculiarity of the sidereal system, and 
when to this we add what has been already sug- 
gested by the relation of contrast between the irre- 
solvable nebulae and the Milky Way, the conclusion 
seems forcibly impressed upon us that the nebular 
and the sidereal systems are but different parts of 
one single scheme. 

But I pass on to other evidence, independent of 
what has hitherto been adduced, and pointing with 
equal force to the same conclusion. 

In the northern heavens it is not very easy to 
exhibit any general law of arrangement associating 
the nebulae and the fixed stars. For reasons which 
yet remain to be detected, there are in fact many 
marked points of difference between the whole char- 
acter of the heavens on the northern and on the 
southern side of the galactic zone. But even in the 
northern heavens one peculiarity has been remarked, 
which is well worthy of careful consideration. Sir 
"William Herschel, while prosecuting his series of 
researches among stars and nebulae, was struck by 
the circumstance that, after sweeping over a part 
of the heavens which was unusually barren, he 
commonly met with nebulae; insomuch that it was 
his practice at such times to call to his assistant (his 
sister, Miss Caroline Herschel) to " prepare for neb- 
ulae." This peculiarity was noticed also by Sir John 
Herschel. 



THE NEBULJE 305 

Now, what are we to understand by such a rela- 
tion as this? Can we suppose that, owing to some 
strange accident, external galaxies have been placed 
always opposite the barest regions of the sidereal 
system? Or, setting aside such a notion as obvi- 
ously incredible, are we to imagine that, when 
searching over those barren regions, the astronomer 
has a better chance of detecting nebulae than where 
stars are more richly strewn, because the sky is less 
filled with glare? We are forced to dismiss this no- 
tion, that the barren regions of the heavens are thus 
in a manner the spy-holes of the sidereal system, by 
the fact (presently, and for another purpose, to be 
dwelt on more at length) that in the Magellanic 
Clouds, where stars of all magnitudes are richly 
strewn, nebulae, even down to the very faintest 
orders, are more abundant than in any other re- 
gion of the heavens. We have, then, no other 
conclusion to form, but that the association thus 
observed between starless regions and richness of 
nebular distribution indicates a very close relation 
indeed between stars and nebulae; that, in fact, the 
nebulas in a sense represent the missing stars; that 
the region where those nebulae appear has been drained 
of star-material, so to speak, in order to form them. 

In the southern heavens yet clearer proof exists 
of an association between the stellar and nebular sys- 
tems. We do not recognize in the northern skies 
any well-marked star-streams. In the southern skies, 
however, such streams have been recognized from 
the earliest ages. The constellations Hydra and 






306 OTHER WORLDS THAN OURS 

Eridanus, the two streams from the Water-can of 
Aquarius, and the band between the two fishes, 1 
indicate how clearly the ancients traced certain well- 
marked star- streams. The moderns have traced the 
extension of some of these streams in the constella- 
tions G-rus, Hydra, Keticulum, etc., into the near 
neighborhood of the southern pole. Now, the neb- 
ulas in the southern heavens exhibit a well-marked 
tendency to aggregate into streams. So that, in this 
mere resemblance between the general characteristics 
of the stellar and nebular systems in the southern 
heavens, we have a somewhat remarkable evidence 
of association. But when we consider the disposition 
of the two sets of streams — the stellar and the nebu- 
lar — this evidence is very much strengthened. There 
is found to be a well-marked correspondence between 
the nebular and stellar streams, not merely as re- 
spects general position, but even in minute details — 
the nebular streams following the windings of the 
stellar ones. Such a relation would be very remark- 
able, even were it observed but in a single instance. 
Since, however, all the well-marked star-streams in 
the southern heavens are associated with well-marked 
nebular streams, no doubt can remain that the rela- 
tion is not a mere coincidence, but indicates a real 
association between the nebular and stellar systems. 

But yet more striking evidence remains to be 
considered. 

In the southern heavens there are two strange 

1 Though Pisces is not a southern constellation, yet it is south of the 
galactic circle, to which I am for the moment referring the constellations. 



THE NEBULJE 307 

clouds of milky light, which have long been known 
by sailors as the Magellanic Clouds, but are com- 
monly called by astronomers the Nubeculae. Each 
of these objects, when examined with the telescope, 
is found to be constituted, like the Milky Way, of 
multitudes of small stars. But, unlike the Milky 
Way, the Nubecula contain within their bounds 
many nebulas of all orders. In fact, each of the 
Nubecula is at once a star-cluster and a cluster 
of nebulae. 

Now, there can be no doubt whatever that the 
association here is not accidental, that we do not 
by some strange chance see a great star-cluster in 
the same direction as a much more distant and much 
vaster cluster of external galaxies. Nor, again, can 
there be any doubt that the generally circular figure 
of each Nubecula indicates a general approach to the 
spherical form in the case of each cluster. The prob- 
ability that by some strange accident a cluster of 
cylindrical shape 1 might be so placed as to exhibit 
to us a circular figure is exceedingly small; but the 
chance that two such clusters should be presented in 
so exceptional a manner may be regarded as evanes- 
cent. We are compelled, then, to believe that, within 
the limits of spheres so placed as to subtend a small 
angle to the eye, stars of all magnitudes between the 
seventh and the twelfth inclusive are mixed up with 
nebulae of all degrees of resolvability. " Taking the 
apparent semi-diameter of the Nubecula Major at 

1 Or, more correctly, a cluster shaped like a long frastrum of a gigantic 
cone. 



OTHER WORLDS THAN OURS 



three degrees," says Sir John Herschel, "and re- 
garding its solid form as, roughly speaking, spher- 
ical, its nearest and most remote parts differ in their 
distance from us by a little more than a tenth part 
of our distance from its centre." "It must therefore 
be taken as a demonstrated fact," he adds presently, 
"that stars of the seventh and eighth magnitude and 
irresolvable nebulae may coexist within limits of dis- 
tance not differing in proportion more than as nine 
to ten." This demonstrated fact of Sir John Her- 
scheFs is the very fact to which I had been led by 
other considerations, the fact, namely, that the neb- 
ulas are not external galaxies, but intimately associ- 
ated with the sidereal system of which in fact they 
form part and parcel. Dr. Whewell, accepting Sir 
John Herschel's reasoning as conclusive on the 
point, adopted the same view. Yet Sir John Her* 
schel himself seems, immediately after establishing 
this noteworthy conclusion, to have been prepared 
to abandon it, at least as a demonstrated fact, since 
he says of it only that "it must inspire some degree 
of caution in admitting as certain" facts directly op- 
posed to it. It must not be forgotten, however, that 
to the clear vision of this great astronomer the asso- 
ciation between nebulae and fixed stars had presented 
itself as a demonstrated fact; that, even in the latest 
editions of his noble work on astronomy, he has not 
altered the words in which he has spoken of that 
association; and that so able a reasoner as Dr. Whew- 
ell has chosen rather to accept what Herschel has 
spoken of as a demonstrated fact, than to adopt that 



THE NEBULA 



309 



measure of caution which Herschel subsequently 
advocated. 

Lastly, and perhaps most strikingly of all, the 
association between stars and nebulae is indicated 
by the obvious connection between the figure of 
the irregular nebulae and the arrangement of the 
star-groups seen in the same field of view. There 
is not one of the irregular nebulae which does not 
exhibit this peculiarity in the most striking manner. 
This may be asserted even of those nebulae with 
respect to which Sir John Herschel has remarked 
that the arrangement may be, and probably is, purely 
accidental. His own pictures prove in the most con- 
vincing manner that no such explanation can be ac- 
cepted. Were the peculiarity confined to the feature 
Herschel limits his attention to, one might adopt his 
explanation. The mere aggregation of a large num- 
ber of stars on the very heart of a nebula might be 
an accident. The fact, for instance, that the great 
irregular nebula surrounding the star Eta Argus 
agrees exactly in position with the greatest con- 
densation of the wonderfully rich portion of the 
Milky "Way on which that surprising variable lies, 
might be a mere coincidence, though in any case it 
would be a strange one. But when one examines 
the structure of this and similar nebulae, and finds 
that the stars are arranged in a manner most obvi- 
ously related to the arrangement of the nebular con- 
densations (or folds as one may almost say), one 
cannot doubt that a real and intimate bond of 
association exists between the stars and the neb- 



310 



OTHER WORLDS THAN OURS 



ulous masses around them. If the extension of 
the milky light of the great Orion nebula to the 
star in the sword, which is centrally involved in 
strong nebulosity, to e in the belt, which is similarly 
involved, and to several other stars in the constella- 
tion all alike in being regions of increased nebular 
condensation, be a mere accidental coincidence, then 
the laws of probability had better be forgotten as 
soon as possible, for, as at present understood, they 
can only serve to lead men astray. 

It will be noticed, as respects the two proofs on 
which I have last dwelt, that they seem directly 
opposed to those which 1 first quoted. One can- 
not argue, it might be urged, that the nebulae are 
associated with the sidereal system because they are 
least numerous where there are most stars, and vice 
versa; while at the same time one draws the same 
conclusion from the aggregation of the nebulae in 
streams or clusters where there are streams and 
clusters of stars, or from the fact that stars are 
seen actually mixed up with nebulous matter. At 
first sight this objection seems just; but, on con- 
sideration, it will be found that, in reality, the two 
seemingly contrary lines of argument bear in the 
same direction. When we find the nebulae gathered 
where stars are wanting, and vice versa, we conclude 
that there is some reason for this peculiarity, and 
that that reason must involve some sort of asso- 
ciation between the nebulae and the stars; we see, 
further, that the relation is accounted for if we 
suppose that, in these cases, either the formation 



THE NERULJB 311 

of nebulae has drained a region of material from 
which single stars would otherwise have been 
formed, or vice versa. Why, in a particular re- 
gion, the formation of nebulae should be encour- 
aged, while the formation of stars should be 
checked, we cannot say; nor can we account 
for the contrary peculiarity in another region; but 
we feel certain that some cause must exist for both 
relations, because the results are too marked to be 
the result of accident. Now, in the case where we 
find both stars and nebulae abundant in particular 
parts of the heavens, we feel equally certain that 
the result is not accidental. Even though there were 
not here, as in the former case, the evidence of a 
clearing of star-material from certain regions, we 
could not doubt that the association of stars and 
nebulae was real and not apparent. But in reality 
there is here, precisely as in the former case, a gath- 
ering together of stellar matter into certain regions. 
The very existence of such a stream as Eridanus or 
Hydra, and of such a cluster as the greater or lesser 
Magellanic Cloud, implies the action of such a proc- 
ess of segregation. A stream would not be recog- 
nizable if it were not bounded by relatively bare 
regions. Clusters like the Nubeculae might be visi- 
ble even on a rich sky, and were the sidereal heav- 
ens richly strewed with stars round these objects I 
should be disposed to admit that there was a diffi- 
culty in my theory. But what is the fact? Not 
only is each of the Nubeculae placed in a region 
obviously bare of lucid stars, but Sir John Herschel, 



812 OTHER WORLDS THAN OURS 

speaking of the telescopic aspect of the neighborhood 
of these mysterious clusters, dwells again and again 
on its poverty. "A miserably poor and barren re- 
gion," he says of one field near the Nubecula. 
"The access to the Nubecula," he says elsewhere, 
*'is on all sides through a desert." What evidence 
could more clearly point to the fact that these great 
clusters are gathered out from a vast region of 
space? Their internal structure teaches us how 
such a process of segregation leads to the birth 
of nebulae, as well as stars. The whole history of 
the sidereal system is indeed taught us in the Magel- 
lanic Clouds and the great streams of intermixed 
stars and nebulae which flow toward them as rivers 
toward some mighty lake. We see the wonder- 
working forces of gravitation extending their in- 
fluences throughout vast regions of space, gather- 
ing in the materials spread throughout that space, 
here forming stars, there nebulae, changing the ele- 
ment of distance into various forms of force—heat 
and light, electricity and magnetism — and finally 
(though in what special way we are as yet un- 
able to perceive) making the orbs which it has 
formed the seats of life, or subservient, more or 
less directly, to the wants of living creatures. 



CHAPTER Xiii 

SUPERVISION AND CONTROL 

IT has been customary, in treatises on the plurality 
of worlds, to discuss the religious difficulties 
which seem to suggest themselves when man 
regards the universe around him as thronged with 
worlds, each peopled with millions of living creat- 
ures, and many perchance the abode of intelligent 
and therefore responsible beings. Accustomed to re- 
gard himself as in a special manner the object of 
God's care and solicitude, it is not without a sense 
of pain that he is brought to contemplate the pos- 
sibility that other creatures may exist in uncounted 
millions whom God regards with infinite love and in- 
terest. "If this be so," asks Whewell, "how shall 
the earth and men, its inhabitants, annihilated as it 
were by the magnitude of the known universe, con- 
tinue to be anything in the regard of Him who em- 
braces all? Least of all, how shall men continue to 
receive that special, preserving, providential, judicial, 
personal care, which religion implies; and without 
the belief in which, any man who has religious 
thoughts must be disturbed and unhappy, desolate 
and forsaken ? " 

Science— l— 14 (818) 



314 OTHER WORLDS THAN OURS 

I do not, however, feel by any means invited to 
consider "the religious difficulty" by the success 
which has attended the efforts made by others to 
remove it. I find that, while, on the one hand, 
the thoughtful and conscientious men who have in 
a special manner considered the difficulty have been 
(in relation at least to revealed religion) at issue 
among each other, their views have not, on the 
other hand, been found acceptable even by a few 
among their readers. I doubt almost, when 1 judge 
from the comments which have been made on this 
part of the works of Chalmers, Whewell, Brewster, 
and others, whether a single reader of those works 
has found the religious views of any one of their 
authors congenial with his own. 

It is specially noteworthy that even where, as in 
the case of Brewster and Chalmers, two writers adopt 
the same view of the general question of other 
worlds, they yet hold altogether different views 
as to the bearing of that question upon the sub- 
ject of religion. 

It is very doubtful, therefore, whether it is a 
wise thing, whether it is conducive to the purpose 
of any one thus conscientiously discussing the re- 
ligious aspect of our question, to present his own 
personal views on the subject of revealed religion. 
If I thought otherwise, I should not shrink from 
the task of indicating the sufficiently tfefinite views 
which I entertain myself upon this subject. But I 
apprehend that, apart from the consideration that the 
reader must be wholly indifferent about them, my 



\ 



SUPERVISION AND CONTROL 315 

indicating them would have an effect the very 
reverse of that which I should desire. 1 

Merely remarking, therefore, that in considering 
the infinity of (rod's beneficence we must remember 
this quality of infinity, that it comprises many infin- 
ities, I pass on to considerations which seem to fall 
more naturally within the province of the student 
of science. 

It is a peculiarity of the subject of other worlds 
than ours, that it suggests, more strikingly than any 
other, certain difficulties in connection with the con- 
ceptions we are to form as to the supervision and 
control exercised by the Creator over His works. 
We feel that if we are to believe, as we must be- 
lieve, in an infinitely powerful and wise God, we 
must not merely regard all the worlds which people 
space as objects of His regard, but every event, how- 
ever seemingly insignificant, occurring in any, even 
the least important of His worlds, as an essential part 
of the plan according to which all things were cre- 
ated from the beginning. 

But here already — such is the nature of the sub- 



1 Where Bacon has selected to be silent, few can without presumption 
venture to lay down their opinions as of weight in matters connected with 
revealed religion. The argument which follows may not indeed be accept- 
able to many, but few will doubt the wisdom of the conclusion to which 
he comes. "If we were disposed," he says, "to survey the realm of 
sacred or inspired theology, we must quit the small vessel of human rea- 
son, and put ourselves on board the ship of the Church, which alone pos- 
sesses the Divine needle for justly shaping the course. Nor will the stare 
of philosophy, that have hitherto principally lent their light, be of further 
service to us ; and therefore it were not improper to be silent upon the sub- 
ject." — Advancement of Learning, Book IX. 



■1 



316 OTHER WORLDS THAN OURS 

ject I am to deal with — I have been forced to use 
terms which have really no proper application to the 
Almighty and His works. I have spoken of the cre- 
ation of all things, whereas, in the sense in which 
men can alone interpret such words, we cannot rea- 
sonably conceive that there ever was a creation; and 
I have spoken of the beginning, whereas we cannot 
conceive that there ever was a beginning in the 
sense implied. 1 

Let us consider definitely (even though we must 
be unable to conceive clearly or at all) the infinities 
we have to deal with. 

We know that space must be infinite. If the re- 
gion amid which stars and nebulae are scattered with 
so great profusion be limited, if beyond lies on all 
sides a vast void, or if, instead, there be material 
bounds enclosing the universe of worlds on every 
hand, yet where are the limits of void or bound? 
Infinity of space, occupied or unoccupied, there must 
undoubtedly be. Of this infinity it has been finely 
said, that its centre is everywhere, its boundary no- 
where. Now, whether within this infinity of space 
there be an infinity of matter, is a question which we 
cannot so certainly answer. Only, if we were to ac- 
cept this as certain, that the proportion which unoc- 
cupied bears to occupied space cannot be infinitely 
great — a view which at least seems reasonable and 
probable — then it would follow that matter as well 

1 To prevent any possibility of my meaning being misinterpreted here, 
I point out that I have been obliged myself to use the terms of which I 
speak as inexact. 



SUPERVISION AND CONTROL 817 

as space must be infinite, since any finite proportion 
of infinity must itself also be infinite. So that, re- 
garding occupied space as the realm over which the 
Almighty's control is exercised, and over which His 
supervision extends, we find just reason for looking 
upon that realm as no less infinite than the infinity 
of space in which it is contained. 

Time also must undoubtedly be infinite. If the 
portion of time which has hitherto been, or which 
will hereafter be, occupied with the occurrence of 
events (of whatever sort) were preceded and will be 
followed by a vast void interval, yet there can 
be neither beginning nor end to either of those 
bounding voids. Infinity of time, occupied or un- 
occupied, there must undoubtedly be. And, though 
it is not possible for us to know certainly that there 
has been no beginning, or that there will be no end 
to that portion of time which is occupied with the 
occurrence of events (of whatever sort), yet it appears 
so unreasonable to conceive that unoccupied time 
bears an infinitely great proportion to occupied time, 
that we seem forced to the conclusion that occupied 
time is infinite — or, more definitely, that there has 
been no beginning and will be no end to the se- 
quence of events throughout the infinitely-extended 
realm of the Almighty. 

And thus we are forced to believe in the infinite 
wisdom and the infinite power of God; since to con- 
ceive of limits to the wisdom and power of Him 
whose realm is infinite in extent and in duration 
is obviously to conclude that the Ruler is infinitely 



twv:\ 



Mr 



318 OTHER WORLDS THAN OURS 

incompetent to rule over His kingdom; for there can 
be no relation between the finite and the infinite save 
the relation of infinite disproportion. 

Now, although the conception of (rod as a spirit — 
omnipresent, eternal, omnipotent, and omniscient — is 
altogether beyond the powers of man's imagination, 
yet we may consider certain relations between the 
way in which He views the universe and the modes 
in which we men consider the various matters fall- 
ing either under our supervision and partial control, 
or of which we can in any way or to any extent 
become cognizant. 

Senses such as we have we can no more attribute 
to God than we can assign to Him hands and feet. 
Nor can we conceive in what way a spirit, as He is, 
is cognizant of material processes which we only 
recognize through their material effects. Yet, as 
we do not doubt that God is cognizant of the actual 
state of the universe at any moment we cannot doubt 
that He is cognizant of all those processes by which 
our senses can be affected. And clearly, He not 
only recognizes all these processes in such sort that 
he may be said to see what we see, to hear what we 
hear, and so on; but effects which, though related 
to vision, hearing, or the like, are infinitely too mi- 
nute to be appreciated by our senses, must be as 
obvious to God as the light of day or the roar of 
thunder to ourselves. 

But, before considering the nature of God's super- 
vision of His universe, we may proceed a step 
further. The senses we possess are sufficient to 



SUPERVISION AND CONTROL 319 

indicate to us the possible existence of senses not 
merely far more acute, but of a wholly different 
kind. By the sense of touch, for instance, we can 
indeed recognize the feeling of heat; but it is easy 
to conceive of a sense (analogous to that by which 
light is made to teach us of the aspect of external 
objects) enabling men to judge of the figure, sub- 
stance, internal structure, and other qualities of an 
object, by the action of the heat-waves proceeding 
from it. Or again electricity might, instead either 
of light or of heat, be the means of communicating 
intelligence as to the qualities of objects. We can 
conceive also of a sense bearing the same analogy 
to sight that the spectroscope bears to the telescope. 
And a hundred kinds of sense, or, in other words, 
a hundred modes of receiving intelligence about what 
exists or is going on around us, might be readily 
conceived. Now, we cannot doubt that the natural 
processes involved in every such mode of conveying 
impressions to material creatures must be infinitely 
more obvious to God than we can possibly conceive 
them to be to material beings. 

Yet once more, we know that reason is able to 
range beyond the action of the senses. Man is able 
to assure himself that events have happened which 
yet have produced no direct effect upon any of his 
senses. By the exercise of reason he becomes as 
well assured of such events as though they had 
actually passed before his eyes. We must assume 
that an analogous power, but infinite in degree, in- 
finitely rapid in its operation, and infinite in the 



JTK^i 



320 OTHER WORLDS THAN OURS 

extent of space and time over which it ranges, is 
possessed by the Almighty. 

And now let us notice some of the conclusions 
to which these considerations tend. 

Let us first deal with the teachings of that sense 
which is the most far-reaching 1 of all the faculties 
given to man — the sense of sight. 

In a little treatise called "The Stars and the 
Earth," published anonymously several years since, 
some results of modern discoveries respecting light 
were dealt with in a very interesting manner. I pro- 
pose to follow the path of thought indicated in that 
treatise, as a fitting introduction to wider conceptions 
of the supervision and control exercised by the Al- 
mighty over His universe. 

We know from Bomer's researches, and even 
more surely from the phenomenon termed the aber- 
ration of the fixed stars, that light does not travel 
with infinite velocity. Its speed is indeed so enor- 
mous, that, compared with every form of motion with 
which we are familiar, the velocity of light appears 
infinitely great. In a single second light traverses a 
space equal to eight times the circumference of the 
earth; and therefore, in travelling from any visible 
object on the earth to the eye of a terrestrial ob- 



1 Most persons, if asked which sense comes next to sight in this 
respect, would answer hearing. Yet touch— or rather feeling — has a range 
far exceeding that of hearing, since we can feel the heat emitted by the 
sun. Nor is it difficult to conceive of such an increase in the delicacy of 
the sense of touch, that even the minute amount of heat received from the 
fixed stars might be felt, and so the range of the sense extended many 
million-fold. 



SUPERVISION AND CONTROL 321 

server, light occupies a space of time indefinitely 
short. Yet, even as regards such objects as these, 
light has occupied a real interval of time, however 
minute, in reaching the eye; insomuch that we see 
objects not as they are at the moment we perceive 
them, but as they were the minutest fraction of a 
second before. 

Eaising our eyes from the earth to regard the 
celestial objects, we find, in place of the indefinitely 
minute interval before considered, a really appreci- 
able space of time occupied by light in carrying to 
us information as to the condition of those distant 
orbs. From the moon, light takes little more than 
a second and a quarter in reaching us, so that we 
obtain sufficiently early information of the condition 
of our satellite. But light occupies more than eight 
minutes in reaching us from the sun, a longer or 
shorter interval in travelling to us from Mercury, 
Venus, and Mars, according to the position of these 
planets, from about thirty-five to about fifty minutes 
in reaching us from Jupiter, about an hour and 
twenty minutes on the average in speeding across 
the great gap which separates us from Saturn, while 
we receive intelligence from Uranus and Neptune 
only after intervals respectively twice and three 
times as great as that which light takes in reaching 
us from the ringed planet. 

Thus, if we could at any instant view the whole 
range of the solar system as distinctly as we see 
Jupiter or Mars when in opposition, the scene pre- 
sented to us would not indicate the real aspect of the 



■I 



322 OTHER WORLDS THAN OURS 

solar system at that, or indeed at any definite instant. 
Precisely as a daily newspaper gives us a later ac- 
count of what is going on in London than of events 
happening in the provinces, of these than of events 
on the Continent, and of these again than of occur- 
rences taking place in America, Asia, Africa, or 
Australasia, so the intelligence brought by light 
respecting the various members of the solar system 
belongs to different epochs. And if man had powers 
of vision enabling him to watch what is taking place 
on the different planets of the solar system, it is clear 
that events of the utmost importance might have 
transpired — under his very eyes, so to speak — while 
yet he remained wholly unconscious of their recur- 
rence. Or, to invert the illustration, if an observer 
on Neptune could see all that is taking place on the 
earth, he might remain for hours quite unconscious 
of an event important enough to affect the welfare of 
a whole continent, though that event should happen 
under his eyes, and his visual powers be such as I 
have supposed. "We can imagine, for example, an 
observer on Neptune watching the battle of Water- 
loo from the early dawn until the hour when Napo- 
leon's heart was yet full of hope, and our great 
captain was watching with ever-growing anxiety, 
as charge after charge threatened to destroy the 
squares on whose steadfastness depended the fate of 
a continent. We can conceive how full of interest 
that scene would have been to an intelligent Mep- 
tunian, and how eagerly he would have watched the 
manoeuvres of either army, and also, what neither 



SUPERVISION AND CONTROL 323 

army knew of, the approach of Blucher with his 
Prussians. Yet, while our Neptunian would thus 
have traced the progress of the battle from his dis- 
tant world, the conflict would in reality have been 
long since decided, the final charge of the British 
army accomplished, the Imperial Guard destroyed, 
Napoleon fugitive, and the Prussians, who to the 
Neptunian would be seen still struggling through 
muddy roads toward the field of battle, would be 
relentlessly pursuing the scattered army of France. 

It is, however, when we pass beyond the limits 
of the solar system that the non-contemporaneous 
nature of the scene presented to us becomes most 
striking. Here we have to deal not with seconds, 
minutes, or hours, but with years, decades, and cent- 
uries. From the nearest of the fixed stars light takes 
fully three years in travelling to the earth. Even the 
star 61 Cygni is so far from us that its light only 
reaches us in ten years. And, so far as observation 
has hitherto gone, it seems unlikely that, amid the 
whole host of heaven, there are so many as a hun- 
dred stars — lucid or telescopic — whose light reaches 
us in a shorter interval of time than twelve or fifteen 
years. Whatever views we form as to the arrange- 
ment of the sidereal scheme, whether those usually 
accepted be held to be correct, or whether I have 
been right in adopting others, there can be no doubt 
that, among the stars revealed to us by the telescope, 
there must be myriads which lie many times further 
from us than the bright star in Centaurus and the 
orb in Cygnus which have been found relatively so 



■■ 



324 OTHER WORLDS THAN OURS 

near to us. In fact, the views I have adopted, re- 
specting the wide range of magnitude among the 
fixed stars, do not interfere in the least with the 
theories which have been formed as to the distances 
from beyond which the light of some of the stars, 
only just visible in powerful telescopes, must be sup- 
posed to reach us. On the contrary, one may con- 
ceive, according to my views, that some of these 
faintly-seen orbs may be many times larger even 
than giant Sirius, in which case the distance of such 
stars would be many times greater than has been 
hitherto supposed. We may at any rate assume with 
confidence that many stars only visible in powerful 
telescopes shine from beyond depths which light 
would occupy thousands of years in traversing. I 
cannot, indeed, go further, as astronomers have 
hitherto done, and say that the nebulae must be 
regarded as external galaxies, and therefore as send- 
ing their light to us over spaces which light must 
take many times as long an interval in traversing as 
it does in travelling to us from the bounds of our 
own galaxy. But it would be to misinterpret alto- 
gether the views which I have formed respecting the 
universe to suppose that I imagine those distant 
spaces which astronomers have hitherto filled with 
imaginary galaxies to be untenanted. On the con- 
trary, I have no doubt whatever that galaxies, re- 
sembling our own, exist at distances infinitely exceed- 
ing those at which astronomers have placed their 
most distant nebular universes, if even the bounds 
of our own galaxy do not extend into space as far as 



SUPERVISION AND CONTROL 



the widest limits hitherto assigned to the system of 
nebulae. So that I am not precluded from speaking 
of orbs whose light, though unrecognized by us, yet 
is ever pouring in upon the earth, conveying, though 
in letters we cannot decipher, or even trace, a mes- 
sage which has taken millions on millions of years 
in traversing the awful gulf beyond which lie those 
mysterious realms* 

If we conceive, then, that man's visual powers 
could suddenly be so increased that, without instru- 
mental aid, he could look around him into the celes- 
tial depths, piercing even to those outer galaxies 
which astronomers have seen only imaged in the 
nebulae, how wide would be the range of time pre- 
sented to him by the wonderful scene he would 
behold. There would blaze out Alpha Centauri with 
its record three years old; there the star in Oygnus 
as it existed ten years since; the whole host of stars 
known to man would exhibit records ranging from 
a few years to many centuries in age; and, lastly, the 
external galaxies, which are perhaps forever hidden 
from the searching gaze of man, would reveal them- 
selves as they were ages on ages before man ap= 
peared upon the earth, ages even before this earth 
was framed into a globe, nay ages perhaps before the 
planetary system had begun to gather into worlds 
around its central orb. 

It is when we are thus contemplating in imagina- 
tion the whole expanse of the universe, and, as one 
may almost say, the whole range of past time, that 
the author of the little treatise I have spoken of 



■■ 



326 OTHER WORLDS THAN OURS 

invites us to consider two processes of thought hav- 
ing sole reference to this earth on which we live, 
and to that history which, though all-important to 
ourselves, seems to fade into such utter insignifi- 
cance in the presence of the grand history of the 
orbs which lie in uncounted millions around us. 

To a being placed on some far-distant orb, whence 
light would occupy thousands of years to wing its 
flight to us, there would be presented, if he turned 
his gaze upon our earth, and if his vision were ade- 
quate to tell him of her aspect, the picture of events 
which thousands of years since really occurred upon 
her surface. For the light which left the earth at 
that time, winging its way through space with the 
account, if we may so speak, of those occurrences, 
is now travelling as swiftly as when it left our earth, 
but amid regions of space removed from us by a 
light-journey thousands of years in duration. And 
thus, to the observer on this distant orb, the events 
which happened in those far-off years would seem 
to be actually in progress. 

But now conceive that powers of locomotion com- 
mensurate with his wonderful powers of vision were 
given to this being, and that in an instant of time 
he could sweep through the enormous interval sep- 
arating him from our earth, until he were no further 
from us than the moon. At the beginning of that 
tremendous journey he would be watching events 
which were occurring thousands of years since; at its 
close he would gaze upon the earth as it was one 
second only before he undertook his instantaneous 



SUPERVISION AND CONTROL 



827 



flight; so that, in the course of his journey, he would 
gaze upon a succession of events which had occurred 
during those thousands of years upon the face of this 
little earth. 

The other conception is no less beautiful and 
striking — I may remark, also, that it is, in a sci- 
entific sense, somewhat more exact. Suppose that a 
being armed with such powers of vision as we have 
imagined should watch from the neighborhood of our 
earth the progress of some interesting event. If he 
then began to travel from the earth at a rate equal 
to that at which light travels, he would see one 
phase of the event continually present before him, 
because he would always be where the light-message 
recording that event was actually travelling. By 
passing somewhat less swiftly away, he would see 
the event taking place with singular slowness; while 
by passing away more swiftly he would see the event 
occurring in inverted order. Suppose, for example, 
he were watching the battle of Waterloo, he could 
gaze on the fine picture presented by the Imperial 
Guard as they advanced upon the English army, for 
hours, years, nay, for centuries or cycles; or he 
might watch the whole progress of the charge occur- 
ring so slowly that years might elapse between each 
step of the advancing column, and the bullets which 
mowed down their ranks might either seem unmov- 
ing, or else appear to wend their way with scarcely 
perceptible motion through the air; or, finally, he 
might so wing his flight through space that the 
Guard would seem to retreat, their dead men com- 



H 



328 OTHER WORLDS THAN OURS 

ing to life as the bullets passed from their wounds, 
until at length the Old Guard would be seen as it 
was when it began its advance, in the assured hope 
of deciding Waterloo, as it had decided so many 
hard-fought battles for its imperial chief. 

It may seem hypercritical to notice scientific in- 
exactness in ideas professedly fanciful. But as the 
author lays some little stress upon the scientific truth 
of the method in which his fancies are exhibited, and 
as, further, he dwells upon two of the more obvious 
objections to the first conception, it may be well to 
consider a further objection, which enforces on us a 
total change in the way of presenting the idea. He 
remarks that the being he has conceived to be borne 
toward the earth through a distance so enormous, 
would not see in a moment the whole history of the 
earth during the thousands of years considered, but 
only the history of that hemisphere which was turned 
toward him; while, further, all that took place under 
roofs or under cover of any sort would remain un- 
perceived by him. But there is a more serious ob- 
jection. Among the events which have taken place 
during those thousands of years, have been thousands 
of revolutions of this earth around the sun, and more 
than three hundred and sixty-five times as many ro- 
tations of this earth upon her axis, to say nothing of 
the stately sway of the earth in her motion of pre- 
cession. So that our imaginary observer would in 
reality see the earth whirling with inconceivable ra- 
pidity upon its axis, and sweeping with even more 
tremendous velocity around the sun, so as to com- 



SUPERVISION AND CONTROL 



829 



plete thousands of circuits in a single second. He 
would see clouds forming and vanishing in an amaz- 
ing succession of changes, all occurring in a single 
instant. And, even though his powers of vision en- 
abled him to pierce the cloud-envelope, he would 
not have a consecutive presentment of the various 
events occurring in any part of the earth, but only 
a haphazard succession of half days for each portion 
of her surface. 

However, we can easily see that, by a slight mod* 
ification, the beautiful conception of our author can 
be made to illustrate one mode at least in which the 
events occurring upon our earth may be conceived 
to be at all times present to the thoughts of the 
Almighty. Imagine a sphere with a radius over 
which light would travel in the time which has 
elapsed since living creatures first began to move 
upon this earth, and having for centre the place 
occupied by the earth at that instant. Then, if we 
imagine millions of eyes over the surface of that 
sphere, all turned with piercing powers of vision 
upon the central earth, we see that to these eyes the 
earth would be presented by the record of light, not 
as she is now, but as she was at that primeval day. 
Now, conceive these millions of eyes closing swiftly 
in upon the earth, but with this peculiarity of move- 
ment that, instead of being always on a sphere 
around a fixed point, they were always on a sphere 
around the position which was really occupied by the 
earth, when the light-messages started which those 
eyes are receiving at the moment. Then if that 



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wondrous sphere contracted in an instant, according 
to the law assigned it, nntil its myriad millions of 
eyes were gazing intently on our earth from a sphere 
of but a few thousand miles in radius, the whole his- 
tory of the earth, so far as light could render it, 
would have been in a moment of time presented 
before the myriad-eyed sphere. 

To apply this illustration to the subject we are 
upon. We know that the Almighty is present where 
the boundary of our great sphere was placed at first. 
Before Him the light- messages are presenting the ac- 
count of the primeval earth. He also is present 
everywhere within the region through which the con- 
tracting sphere was conceived to pass, lie therefore 
sees the whole history of the earth as presented by 
the light-waves. We begin, however, already to feel 
that we cannot say of Him what we said of the im- 
aginary being first thought of, or of the myriad -eyed 
contracting sphere, that in a moment of time He can 
see the whole history of the earth successively pre- 
sented before Him. As He exists throughout that 
space, there is no succession of time in His vision 
of the events transpiring on our globe. Past and 
present are one before Him; and we shall soon see 
that present and future also must be one in His 
sight. 

But now, still considering only the information 
which light conveys as it travels onward through 
space, we see that what is true of our earth is true 
also of every orb throughout the universe. The 
whole light-history of every such orb must be pres- 



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ent at every instant of time to the Creator who is 
omnipresent. So that to the obvious conception that 
God, being everywhere, must be cognizant of all 
things, we have to add this further consequence of 
His omnipresence, that He must be cognizant of the 
history of all things, in the same sense that a man 
is cognizant of events which are passing before his 
eyes. 

And, by extending these considerations to other 
modes in which the history of an event is recorded, 
so to speak, by natural processes, we can see that a 
much more complete and definite picture of past 
events than light can convey must be at all times 
present before the A] mighty. A sense which could 
analyze heat-impressions as eyesight analyzes light, 
would tell us not only what eyesight tells us, but 
much that no light-messages can convey to us. At 
k i-st it is conceivable that a sense of this sort would 
enable the being provided with it to recognize not 
merely the nature of the surface of any body whose 
heat reached the organ of this sense, but the quality 
of the body's internal structure, processes going on 
within the body, or the nature of bodies so placed 
that eyesight would not render us sensible even of 
their existence. Electricity, in like manner, would 
avail to give information altogether distinct from that 
which light can impart. And precisely as, in consid- 
ering light, we saw that the Creator must be sup- 
posed sensible of every light-record travelling through 
space, so, as regards these imaginary but conceivable 
senses, we must believe that any information which 



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OTHER WORLDS THAN OURS 



they could by any possibility impart must be con- 
veyed to the omnipresent God. And, further, it 
would be a contradiction to our belief in His infi- 
nite wisdom to suppose that the infinite multiplicity 
of the records thus continually present before Him 
could in any way render their significance less 
distinct.* 

But, turning from the consideration that the Al- 
mighty, by virtue of His omnipresence, is # thus cog- 
nizant, not merely of all that is at any moment 
taking place throughout the universe, but of all 
that has taken place in the infinity of past time, we 
have to consider another mode in which the universe 
must be regarded as present before Almighty God. 

The senses by which we judge of what is going 
on around us are, after all, merely one means by 
which we judge of causes by their effects. When 
we say, for instance, that we have seen such and 
such an object, or watched such and such an event, 
what we really imply is, that we have recognized 
certain physical impressions, which we can only ex- 



1 Moralizing may seem altogether out of place in such a work as this, 
but certainly one is tempted to dwell somewhat thoughtfully on the ideas 
raised by the considerations I have dwelt on above. It is not without a 
feeling of awe that one considers that the records of every action of our 
lives are not merely at this moment before God, but will for ever and ever 
be freshly present to Him: and that, not merely in the sense that He 
knows everything (an idea too vague for man rightly to grasp), but by 
the action of physical processes such as our Faraday s and Tyndalls deal 
with. May it not be through an instinctive recognition of this great truth 
that man alone, of all the creatures which people this earth, feels contri- 
tion for long-past misdeeds, even where he has no fear of their ever bear- 
ing fruit in future sorrows? 



SUPERVISION AND CONTROL 333 

plain by the existence of that object, or by the 
occurrence of that event. We know, in fact, that 
in certain exceptional cases impressions resembling 
those caused by the actual presence of an object, or 
by the actual occurrence of some event, may arise 
where no such object has been present, or where no 
such event has transpired. Still, we commonly feel 
safe from error, in concluding, from certain impres- 
sions conveyed to the mind by the agency of the 
visual organs, that certain objects have been really 
present, at rest or in action, before us. 

But, then, even man, limited as are his powers, 
can yet follow a series of effects and causes far more 
numerous than those concerned in the act of vision; 
and so he can become certain of the occurrence of 
past events of which no sense he possesses gives him 
any direct information. For example, though I 
neither saw the battle of Waterloo nor heard the 
thunder of the guns there, yet I am as certain that 
the battle really took place as though sight and hear- 
ing had given me direct information on the matter. 
And, when I inquire whence that certainty arises, I 
find a complicated series of events involved in my 
acquisition of the knowledge that the battle took 
place. My interpretation of the letter- press account 
of the battle involved in itself a number of more or 
less complex relations, associated with the question 
of my confidence in those who taught me that cer- 
tain symbols represented certain letters, that certain 
combinations of letters represented certain words, and 
that certain words represented certain ideas. Not to 



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834 OTHER WORLDS THAN OURS 

follow oat the long train of ideas thus suggested, it 
will be clear that, with regard to a variety of matters, 
the knowledge which any man has is associated with 
considerations of cause and effect, of general experi- 
ence, of confidence in the accounts of others or in 
his own judgment, which are in reality of a highly- 
complex character. 

Now, we are led by these thoughts to remember 
that, independently of those records of past events 
which are brought continually before the Almighty 
by processes resembling those which directly affect 
our senses, such events must be recognizable by Him 
(even to their minutest details) in the consequences 
which they have led to. If a great naturalist like 
Huxley or Owen can tell, by examining the tooth of 
a creature belonging to some long -extinct race, not 
only what the characteristics of that race were, but 
the general nature of the scenery amid which such 
creatures lived, we see at once that a single gram of 
sand or drop of water must convey to the Omniscient 
the history of the whole world of which it forms 
part. Nay, why should we pause here? The his- 
tory of that world is in truth bound up so intimately 
with the history of the universe, that the grain of 
sand or drop of water conveys not only the history 
of a world, but with equal completeness the his- 
tory of the whole universe. 

The Almighty, then, by virtue of His possessing 
in an infinite degree that quality which enables man 
to reason upon past events of which his senses bring 
him no direct intelligence, has the whole past history 



SUPERVISION AND CONTROL 



335 



of the universe continually present before Him, in 
the state and position of each single atom throughout 
infinity of space. 1 

Turning from the past to the future, we must not 
let the limited nature of our recognition of the 
course of future events prevent us from forming 
a just opinion as to the way in which the future 
must be always present before God. We can judge 
of the past by its effects, but we are almost utterly 
unable to judge of the future by its causes. Yet we 
cannot doubt that the future is present in its germs, 
precisely as the past is present in its fruits. It may 
be regarded in fact as merely a peculiarity of man's 
constitution that the past is more clearly present to 
his mental vision than the future. It is easy not 
only to conceive that the future and the past should 
be equally present to intelligent creatures, but to 
conceive of a form of intelligence according to which 
past events would be obliterated from the mind as 
fast as they took place, while the future should be 
as actually present as to the ordinary human mind 
the past is. 

In considering the Omniscient, however, all ques- 
tions of degree must be set on one side. The future 
must be as absolutely and essentially present to Him 
in its germs as the past has been shown to be in its 



1 In fact, if we consider the matter attentively, we see that there can- 
not be a single atom throughout space which could have attained its pres- 
ent exact position and state, had the history of any part of the universe, 
however insignificant, been otherwise than it has actually been, in even 
the minutest degree. 



33d 



OTHER WORLDS THAN OURS 



fruits. If a grain of sand contains in its state, fig- 
ure, and position, the picture of the universe as it 
is, and the whole history of the universe throughout 
the infinite past — and who can doubt that this is so? 
— it contains with equal completeness the history of 
the universe throughout the infinite future. No 
other view is compatible with the assumption of 
the Almighty's infinite wisdom, and no assumption 
which limits the wisdom of God is compatible with 
our belief that He is supreme in the universe. 

Obviously also every event, however trifling, must 
be held to contain in itself the whole history of the 
universe throughout the infinite past, and throughout 
the infinite future. For every event, let its direct 
importance be what it may, is indissolubly bound up 
with events preceding, accompanying, and following 
it, in endless series of causation, interaction, and 
effect. 

So far, then, as the Almighty's watch over His 
universe is concerned, we have two lines of thought, 
each leading to the recognition of a perfect supervis- 
ion. In virtue (1) of His omnipresence, and (2) of 
His infinite wisdom, He sees at each instant the 
whole universe as it has been in the infinite past, 
as it is now, and as it will be in the infinite future; 
and this being as true of any one instant as it is of 
any other, we recognize the operation of yet a new 
form of infinity— the infinite duration of the Al- 
mighty's existence — to render yet more inconceiv- 
ably perfect God's supervision of His universe. 

And now with regard to control. Does the Al- 



SUPERVISION AND CONTROL 



337 



mighty, who supervises all things, exercise any 
controlling action upon the course of events? 

It need hardly be said that, if Grod does exercise 
control, apart from the laws which He has assigned 
to His universe, His knowledge of the progress of 
past and future events is not therefore to be called 
in question, since His own direct action, whether in 
the past or in the future, is quite as much the sub- 
ject of His consciousness (to use this word for want 
of a better) as the action of His creatures or of the 
laws He has primarily set them. 

We know that certain laws have been assigned to 
the universe, and we know also that, so far as our 
very limited experience enables us to determine, 
these laws are never abrogated. 1 Here I set alto- 



1 All things working thus according to law, however, certain difficul- 
ties suggest themselves which must not be left undealt with, since not to 
consider them might he to leave painful doubts in the minds of some who 
may read these pages. 

In the first place, there is the old question of the relation between 
man's free-will and the absolute foreknowledge of Almighty God. It 
seems clear to many that if all things are foreknown there can be no such 
thing as free-will ; insomuch that some have even felt forced to believe 
that the Almighty, though undoubtedly omniscient, must in a sense 
forego His knowledge of future events so that the actions of men may be 
subject to the control of their will. But in reality we have only to con- 
sider the analogy of human foreknowledge, to see that there is no neces- 
sity for any theory so self -contradictory as this. We have already con- 
sidered other attributes of the Almighty as in a sense resembling, though 
infinitely exceeding in range of action, certain attributes of man ; let us, 
then, inquire whether that attribute of man which, though imperfect and 
limited, yet corresponds to the foreknowledge of God, affords us any rea- 
son for believing that perfect foreknowledge bars the exercise of free-will 
The answer is obvious at once. We know that we often judge, with more 
or less certainty of conviction, that such and such acts will be performed 
by others, and that yet our anticipation in no sense influences the will of 

Science— 1 — 15 



1 



338 OTHER WORLDS THAN OURS 

gether aside, for the moment, the possibility of mira- 
cles, and consider only the results of experimental 
or observational science. Thus, we are led to the 
conclusion that all things happen according to set 

the persons who are expected so to act. Suppose I remember, for exam- 
ple, that I have left a valuable in a room which will presently be passed 
through by one whom I know to be dishonest; I judge accordingly that 
the person will purloin the valuable. In this case his free-will is not 
affected* by my anticipation; nor would it be though a yet clearer convic- 
tion of his conduct were impressed upon me. There is, in fact, no con 
ceivable degree of certainty on my part which would render him unde- 
serving of punishment for stealing the valuable. And so, not to give 
further instances where the matter is so obvious, we see that no conceiv- 
able degree of foreknowledge bars free-wilL The infinite and absolute 
foreknowledge of the Almighty is therefore altogether dissociated from the 
dangerous and hurtful belief in a predestination which renders man irre- 
sponsible for his actions. 

Secondly, the belief in the absolute perfection of the laws according to 
which God rules His universe, insomuch that throughout all the worlds 
in space all things work according to those laws without need of specia; 
interference on His part, has been thought by many, and is painfully felt 
by some, to oppose itself to our belief in the efficacy of prayer. In touch- 
ing on this point, I wish very carefully to avoid any intrusion on matters 
apart from the general scope of my subject; but a few words may be per- 
mitted me on a point which comes close home to the hearts of all of us, 
and which also does seem in a sense associated with the matters I have 
been dealing with. AE men, I suppose, pray ; though many may in words 
deride prayer, and though hundreds, without expressing doubts, may fail 
to see any possible utility in the practice, because they cannot believe 
that the action of the physical laws of God can be interfered with in an- 
swer to the appeal of His creatures. It is because I fear lest some of my 
readers should have felt this difficulty, and should find their doubts con- 
firmed by anything I may here have written, that I indicate the explana- 
tion which I suppose every one who thinks much upon this point would 
probably be led to. Remembering that, on the one hand, it is unreason- 
able to conceive that God would have allowed a belief in the efficacy of 
prayer to grow, as it has done, to be a part of human nature, were that 
belief founded in a monstrous fiction, and that, on the other hand, it is 
unreasonable to suppose that physical laws are interfered with in response 
to the millions of prayers daily offered by men, the obvious conclusion 
seems to be that prayers are responded to (where it has seemed fitting that 



SUPERVISION AND CONTROL 339 

physical laws: and without, by any means, adopting 
the view that the Almighty exercises no special con- 
trol over His universe, we see strong reason to be- 
lieve that the laws which He has assigned to it are 

they should be) without interference with natural laws ; that, in fact, the 
scheme of the Almighty includes at once the prayers and their response. 
It seems baffling, indeed, to human thoughts that such an infinity of varied 
interests should thus be provided for, in a scheme whose extent covers the 
infinity of past and future time; but where infinite wisdom is in question 
this consideration need not trouble us. Nor is this particular mode of 
control inconsistent even with our merely human conceptions of what 
is reasonable. For instance, a father, desirous at once of testing and 
rewarding the obedience of a son, might tell him to go to such a place and 
to open such a box, having beforehand placed therein a reward for his 
son's obedience. Here the fulfilment of the father's request would no 
more result in bringing the gift to the box, than our fulfilment of the duty 
of prayer can cause the laws of Nature to cease or change in their opera- 
tion; yet obedience would in the one case, as we can conceive it does in 
the other, in reality bring about its own reward. And, further, it may 
be remarked that, precisely as the greater or less certainty of the father 
as to his son's obedience would in no sense affect the latter 's merit, so 
neither does the absolute foreknowledge of God as to the prayers which 
His creatures will offer up, affect in any sense the merit which He has 
been pleased to recognize in the sincere performance of the act of prayer. 
Lastly, there is the difficulty as to our belief in miracles — that is, in 
events which involve the temporary suspension or alteration of natural 
laws. It must be remembered here that recent physical researches, 
though they have enabled us to interpret so many of the laws of Nature, 
yet tell neither for nor against our recognition of the possibility of mira- 
cles. It belongs to the very essence of a miracle that it should be an 
event which no physical researches can explain, or indeed can affect 
otherwise than to render it the more inexplicable. The question is, not 
whether such and such an event is more or less wonderful to the un- 
learned Hodge or Styles on the one part, or to a Newton or a Faraday 
on the other, but whether an event can really take place in which the 
laws of Nature have absolutely been annulled and abrogated. I take it, 
for instance, that if we could see a hungry multitude fed with a few 
loaves, and were absolutely certain that so many thousands had been sat- 
isfied with what would naturally be the food but of a few, our wonder 
would not be greater or less whether we viewed the matter as a laborer 
would, who simply knows what hunger is and what is needed to satisfy 



340 OTHER WORLDS THAN OURS 

sufficient for the control of all things. Indeed* so far 
as all things take place in accordance with laws 
which the Almighty must assuredly have Himself 
ordained, we may say that every event which has 
happened or will happen throughout infinite lime is 
the direct work, and indicates the direct purpose and 

it, or whether we were familiar with the analysis of bread and comparted 
the amount of fibrins and albumen contained in the loaves with what we 
knew of the daily or hourly exhaustion of the corresponding matertak 
in the human frame. 

The arguments in favor of miracles or against their having occurred 
(of their possibility there need be no question) are the same now as they 
were in less scientific ages, Those who believe in the occurrence of mira- 
cles argue thus: Man differs from all other terrestrial creatures in being 
responsible to his Creator. Thus between him and Almighty God there is 
a direct relation, which renders it necessary that the will of God should 
be communicated to man. Now, we can conceive no way in which such 
communication can be made in an unmistakable manner, but fey events 
which involve an unmistakable exercise of a power belonging to God alone 
—that is, by events of a supernatural character. The believer in miracles 
further argues that nothing tending to prove the impossibility (in a natural 
sense) of an event of this sort can be accepted to disprove its occurrence, 
since what is essentially requisite to the very purpose of a miracle is that 
it should be in a natural sense impossible. Nor is it necessary that any 
recorded miracle should be in itself of a striking or imposing character, so 
long as its connection with the communication of God's will in a special 
manner is reasonably established, since the triviality or non-triviality of 
an event whose miraculous character is in question is to be judged only 
by the circumstances of those for whose instruction the miracle Is sup- 
posed to have been worked. 

The argument against the occurrence of miracles has been already 
considered. As has been pointed out, it not only does not meet the argu- 
ment just stated, but rests on the very fact which constitutes the basis of 
that argument— the feet, namely, that the occurrence of miracles is con- 
trary to experience. It is obvious, then, that the considerations I have 
urged, as to the nature of God's control over His universe, need not be 
regarded as in the slightest degree affecting the belief of men in those 
direct relations between God and man which have been held to involve 
the necessity of miracles. To speak further, however, on this matter 
would bring me to deal with that subject which I have selected to avoid. 



SUPERVISION AND CONTROL 341 

will, of Almighty God. Nor need the thought that 
the Almighty thus seems to be made the author of 
evil as well as of good in any way startle us, be- 
cause we know that what constitutes evil or good 
in our limited vision may by no means be accepted 
as indicative of what is evil or good as the work 
of God. We know, limited as our wisdom is, that 
evil often works to good, so that if the Almighty, 
whose wisdom extends over the never-ending chain 
of sequent events, seems, by permitting evil, to, in 
a sense, countenance it, we are to recognize the 
sequent good as in truth His work, and to regard 
that which is objectively evil (and actually evil in 
the creature who does it) as subjectively good in 
Him who permits it with a perfect knowledge 
of all that in the infinity of future time is to 
flow from it. 

Now, it seems conceivable that in reality it is 
only our limited acquaintance with the operation of 
the laws which God has set His universe, which 
makes us regard them as unchanging, and, so to 
speak, inexorable. There seems, indeed, reason 
rather to expect than to deny, that He who made 
the laws may annul or suspend them at His 
pleasure. 

But I think that this view — though it has been 
entertained by many thoughtful men, especially be- 
cause it seems to give the Almighty a special con- 
trolling power over His universe — is in reality incon- 
sistent with just conceptions of His infinite wisdom. 
If His wisdom, though inconceivably great, were yet 



342 OTHER WORLDS THAN OURS 

finite, we could not suppose that the universe would 
have been so planned (still to use inexact words for 
want of better), and laws of such a nature assigned 
to it, that throughout the infinity of time all things 
should work out the will and purpose of Almighty 
God. There would then, undoubtedly, be continual 
need of adaptation, change, remodelling — of the an- 
nulment of a law here, or its suspension there — in 
order that the whole might not fall to wrack. But 
where the God of Nature is infinitely wise, there can 
be no such necessity. The whole scheme of the 
universe must needs be so perfect that direct inter- 
vention cannot at any time be required. 

To sum up, we find ourselves led to the belief 
that, while intervention with the operation of natural 
laws is unnecessary, all the worlds existing through- 
out space are, in a very definite and special manner, 
watched over and controlled by an omnipresent, om- 
nipotent, and omniscient Being; that before Him the 
infinite past and the infinite future of the universe 
are at all times sensibly present; that each the mi- 
nutest atom and every the least important event ex- 
hibits 'before Him at each instant the perfect history 
of the limitless past and future of the universe; and 
lastly, that His infinitely perfect consciousness of, 
and control over, all that has been, is, or will 
be, are infinitely multiplied (to use the only avail- 
able expression) by the infinite duration throughout 
which His existence extends. 

THE END 



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